Calculus Examples

$lim_{x \to \infty} \frac{2 x e^{x^{2}}}{4 x^{3}}$

Step 1

Evaluate the limit of the numerator and the limit of the denominator.

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Step 1.1

Take the limit of the numerator and the limit of the denominator.

$\frac{lim_{x \to \infty} 2 x e^{x^{2}}}{lim_{x \to \infty} 4 x^{3}}$

Step 1.2

Evaluate the limit of the numerator.

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Step 1.2.1

Evaluate the limit.

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Step 1.2.1.1

Split the limit using the Product of Limits Rule on the limit as $x$ approaches $\infty$ .

$\frac{lim_{x \to \infty} 2 \cdot lim_{x \to \infty} x \cdot lim_{x \to \infty} e^{x^{2}}}{lim_{x \to \infty} 4 x^{3}}$

Step 1.2.1.2

Evaluate the limit of $2$ which is constant as $x$ approaches $\infty$ .

$\frac{2 \cdot lim_{x \to \infty} x \cdot lim_{x \to \infty} e^{x^{2}}}{lim_{x \to \infty} 4 x^{3}}$

Step 1.2.1.3

The limit at infinity of a polynomial whose leading coefficient is positive is infinity.

$\frac{2 \cdot \infty \cdot lim_{x \to \infty} e^{x^{2}}}{lim_{x \to \infty} 4 x^{3}}$

Step 1.2.2

Since the exponent $x^{2}$ approaches $\infty$ , the quantity $e^{x^{2}}$ approaches $\infty$ .

$\frac{2 \cdot \infty \cdot \infty}{lim_{x \to \infty} 4 x^{3}}$

Step 1.2.3

Simplify the answer.

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Step 1.2.3.1

A non-zero constant times infinity is infinity.

$\frac{\infty \cdot \infty}{lim_{x \to \infty} 4 x^{3}}$

Step 1.2.3.2

Infinity times infinity is infinity.

$\frac{\infty}{lim_{x \to \infty} 4 x^{3}}$

Step 1.3

The limit at infinity of a polynomial whose leading coefficient is positive is infinity.

$\frac{\infty}{\infty}$

Step 1.4

Infinity divided by infinity is undefined.

Undefined

$\frac{\infty}{\infty}$

Step 2

Since $\frac{\infty}{\infty}$ is of indeterminate form, apply L'Hospital's Rule. L'Hospital's Rule states that the limit of a quotient of functions is equal to the limit of the quotient of their derivatives.

$lim_{x \to \infty} \frac{2 x e^{x^{2}}}{4 x^{3}} = lim_{x \to \infty} \frac{\frac{d}{d x} [2 x e^{x^{2}}]}{\frac{d}{d x} [4 x^{3}]}$

Step 3

Find the derivative of the numerator and denominator.

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Step 3.1

Differentiate the numerator and denominator.

$lim_{x \to \infty} \frac{\frac{d}{d x} [2 x e^{x^{2}}]}{\frac{d}{d x} [4 x^{3}]}$

Step 3.2

Since $2$ is constant with respect to $x$ , the derivative of $2 x e^{x^{2}}$ with respect to $x$ is $2 \frac{d}{d x} [x e^{x^{2}}]$ .

$lim_{x \to \infty} \frac{2 \frac{d}{d x} [x e^{x^{2}}]}{\frac{d}{d x} [4 x^{3}]}$

Step 3.3

Differentiate using the Product Rule which states that $\frac{d}{d x} [f (x) g (x)]$ is $f (x) \frac{d}{d x} [g (x)] + g (x) \frac{d}{d x} [f (x)]$ where $f (x) = x$ and $g (x) = e^{x^{2}}$ .

$lim_{x \to \infty} \frac{2 (x \frac{d}{d x} [e^{x^{2}}] + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [4 x^{3}]}$

Step 3.4

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = e^{x}$ and $g (x) = x^{2}$ .

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Step 3.4.1

To apply the Chain Rule, set $u$ as $x^{2}$ .

$lim_{x \to \infty} \frac{2 (x (\frac{d}{d u} [e^{u}] \frac{d}{d x} [x^{2}]) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [4 x^{3}]}$

Step 3.4.2

Differentiate using the Exponential Rule which states that $\frac{d}{d u} [a^{u}]$ is $a^{u} \ln (a)$ where $a$ = $e$ .

$lim_{x \to \infty} \frac{2 (x (e^{u} \frac{d}{d x} [x^{2}]) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [4 x^{3}]}$

Step 3.4.3

Replace all occurrences of $u$ with $x^{2}$ .

$lim_{x \to \infty} \frac{2 (x (e^{x^{2}} \frac{d}{d x} [x^{2}]) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [4 x^{3}]}$

Step 3.5

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$lim_{x \to \infty} \frac{2 (x (e^{x^{2}} (2 x)) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [4 x^{3}]}$

Step 3.6

Raise $x$ to the power of $1$ .

$lim_{x \to \infty} \frac{2 (x^{1} x (e^{x^{2}} \cdot (2)) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [4 x^{3}]}$

Step 3.7

Raise $x$ to the power of $1$ .

$lim_{x \to \infty} \frac{2 (x^{1} x^{1} (e^{x^{2}} \cdot (2)) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [4 x^{3}]}$

Step 3.8

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$lim_{x \to \infty} \frac{2 (x^{1 + 1} (e^{x^{2}} \cdot (2)) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [4 x^{3}]}$

Step 3.9

Add $1$ and $1$ .

$lim_{x \to \infty} \frac{2 (x^{2} (e^{x^{2}} \cdot (2)) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [4 x^{3}]}$

Step 3.10

Multiply $e^{x^{2}}$ by $2$ .

$lim_{x \to \infty} \frac{2 (x^{2} (e^{x^{2}} \cdot 2) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [4 x^{3}]}$

Step 3.11

Move $2$ to the left of $e^{x^{2}}$ .

$lim_{x \to \infty} \frac{2 (x^{2} (2 e^{x^{2}}) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [4 x^{3}]}$

Step 3.12

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 1$ .

$lim_{x \to \infty} \frac{2 (x^{2} (2 e^{x^{2}}) + e^{x^{2}} \cdot 1)}{\frac{d}{d x} [4 x^{3}]}$

Step 3.13

Multiply $e^{x^{2}}$ by $1$ .

$lim_{x \to \infty} \frac{2 (x^{2} (2 e^{x^{2}}) + e^{x^{2}})}{\frac{d}{d x} [4 x^{3}]}$

Step 3.14

Simplify.

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Step 3.14.1

Apply the distributive property.

$lim_{x \to \infty} \frac{2 (x^{2} (2 e^{x^{2}})) + 2 e^{x^{2}}}{\frac{d}{d x} [4 x^{3}]}$

Step 3.14.2

Combine terms.

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Step 3.14.2.1

Multiply $2$ by $2$ .

$lim_{x \to \infty} \frac{4 (x^{2} (e^{x^{2}})) + 2 e^{x^{2}}}{\frac{d}{d x} [4 x^{3}]}$

Step 3.14.2.2

Remove parentheses.

$lim_{x \to \infty} \frac{4 x^{2} e^{x^{2}} + 2 e^{x^{2}}}{\frac{d}{d x} [4 x^{3}]}$

Step 3.14.3

Reorder terms.

$lim_{x \to \infty} \frac{4 e^{x^{2}} x^{2} + 2 e^{x^{2}}}{\frac{d}{d x} [4 x^{3}]}$

Step 3.14.4

Reorder factors in $4 e^{x^{2}} x^{2} + 2 e^{x^{2}}$ .

$lim_{x \to \infty} \frac{4 x^{2} e^{x^{2}} + 2 e^{x^{2}}}{\frac{d}{d x} [4 x^{3}]}$

Step 3.15

Since $4$ is constant with respect to $x$ , the derivative of $4 x^{3}$ with respect to $x$ is $4 \frac{d}{d x} [x^{3}]$ .

$lim_{x \to \infty} \frac{4 x^{2} e^{x^{2}} + 2 e^{x^{2}}}{4 \frac{d}{d x} [x^{3}]}$

Step 3.16

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 3$ .

$lim_{x \to \infty} \frac{4 x^{2} e^{x^{2}} + 2 e^{x^{2}}}{4 (3 x^{2})}$

Step 3.17

Multiply $3$ by $4$ .

$lim_{x \to \infty} \frac{4 x^{2} e^{x^{2}} + 2 e^{x^{2}}}{12 x^{2}}$

Step 4

Apply L'Hospital's rule.

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Step 4.1

Evaluate the limit of the numerator and the limit of the denominator.

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Step 4.1.1

Take the limit of the numerator and the limit of the denominator.

$\frac{lim_{x \to \infty} 4 x^{2} e^{x^{2}} + 2 e^{x^{2}}}{lim_{x \to \infty} 12 x^{2}}$

Step 4.1.2

Evaluate the limit of the numerator.

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Step 4.1.2.1

Evaluate the limit.

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Step 4.1.2.1.1

Split the limit using the Sum of Limits Rule on the limit as $x$ approaches $\infty$ .

$\frac{lim_{x \to \infty} 4 x^{2} e^{x^{2}} + lim_{x \to \infty} 2 e^{x^{2}}}{lim_{x \to \infty} 12 x^{2}}$

Step 4.1.2.1.2

Split the limit using the Product of Limits Rule on the limit as $x$ approaches $\infty$ .

$\frac{lim_{x \to \infty} 4 \cdot lim_{x \to \infty} x^{2} \cdot lim_{x \to \infty} e^{x^{2}} + lim_{x \to \infty} 2 e^{x^{2}}}{lim_{x \to \infty} 12 x^{2}}$

Step 4.1.2.1.3

Evaluate the limit of $4$ which is constant as $x$ approaches $\infty$ .

$\frac{4 \cdot lim_{x \to \infty} x^{2} \cdot lim_{x \to \infty} e^{x^{2}} + lim_{x \to \infty} 2 e^{x^{2}}}{lim_{x \to \infty} 12 x^{2}}$

Step 4.1.2.1.4

The limit at infinity of a polynomial whose leading coefficient is positive is infinity.

$\frac{4 \cdot \infty \cdot lim_{x \to \infty} e^{x^{2}} + lim_{x \to \infty} 2 e^{x^{2}}}{lim_{x \to \infty} 12 x^{2}}$

Step 4.1.2.2

Since the exponent $x^{2}$ approaches $\infty$ , the quantity $e^{x^{2}}$ approaches $\infty$ .

$\frac{4 \cdot \infty \cdot \infty + lim_{x \to \infty} 2 e^{x^{2}}}{lim_{x \to \infty} 12 x^{2}}$

Step 4.1.2.3

Since the function $e^{x^{2}}$ approaches $\infty$ , the positive constant $2$ times the function also approaches $\infty$ .

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Step 4.1.2.3.1

Consider the limit with the constant multiple $2$ removed.

$\frac{4 \cdot \infty \cdot \infty + lim_{x \to \infty} e^{x^{2}}}{lim_{x \to \infty} 12 x^{2}}$

Step 4.1.2.3.2

Since the exponent $x^{2}$ approaches $\infty$ , the quantity $e^{x^{2}}$ approaches $\infty$ .

$\frac{4 \cdot \infty \cdot \infty + \infty}{lim_{x \to \infty} 12 x^{2}}$

Step 4.1.2.4

Simplify the answer.

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Step 4.1.2.4.1

Simplify each term.

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Step 4.1.2.4.1.1

A non-zero constant times infinity is infinity.

$\frac{\infty \cdot \infty + \infty}{lim_{x \to \infty} 12 x^{2}}$

Step 4.1.2.4.1.2

Infinity times infinity is infinity.

$\frac{\infty + \infty}{lim_{x \to \infty} 12 x^{2}}$

Step 4.1.2.4.2

Infinity plus infinity is infinity.

$\frac{\infty}{lim_{x \to \infty} 12 x^{2}}$

Step 4.1.3

The limit at infinity of a polynomial whose leading coefficient is positive is infinity.

$\frac{\infty}{\infty}$

Step 4.1.4

Infinity divided by infinity is undefined.

Undefined

$\frac{\infty}{\infty}$

Step 4.2

$lim_{x \to \infty} \frac{4 x^{2} e^{x^{2}} + 2 e^{x^{2}}}{12 x^{2}} = lim_{x \to \infty} \frac{\frac{d}{d x} [4 x^{2} e^{x^{2}} + 2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3

Find the derivative of the numerator and denominator.

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Step 4.3.1

Differentiate the numerator and denominator.

$lim_{x \to \infty} \frac{\frac{d}{d x} [4 x^{2} e^{x^{2}} + 2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.2

By the Sum Rule, the derivative of $4 x^{2} e^{x^{2}} + 2 e^{x^{2}}$ with respect to $x$ is $\frac{d}{d x} [4 x^{2} e^{x^{2}}] + \frac{d}{d x} [2 e^{x^{2}}]$ .

$lim_{x \to \infty} \frac{\frac{d}{d x} [4 x^{2} e^{x^{2}}] + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.3

Evaluate $\frac{d}{d x} [4 x^{2} e^{x^{2}}]$ .

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Step 4.3.3.1

Since $4$ is constant with respect to $x$ , the derivative of $4 x^{2} e^{x^{2}}$ with respect to $x$ is $4 \frac{d}{d x} [x^{2} e^{x^{2}}]$ .

$lim_{x \to \infty} \frac{4 \frac{d}{d x} [x^{2} e^{x^{2}}] + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.3.2

Differentiate using the Product Rule which states that $\frac{d}{d x} [f (x) g (x)]$ is $f (x) \frac{d}{d x} [g (x)] + g (x) \frac{d}{d x} [f (x)]$ where $f (x) = x^{2}$ and $g (x) = e^{x^{2}}$ .

$lim_{x \to \infty} \frac{4 (x^{2} \frac{d}{d x} [e^{x^{2}}] + e^{x^{2}} \frac{d}{d x} [x^{2}]) + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.3.3

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = e^{x}$ and $g (x) = x^{2}$ .

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Step 4.3.3.3.1

To apply the Chain Rule, set $u_{1}$ as $x^{2}$ .

$lim_{x \to \infty} \frac{4 (x^{2} (\frac{d}{d u_{1}} [e^{u_{1}}] \frac{d}{d x} [x^{2}]) + e^{x^{2}} \frac{d}{d x} [x^{2}]) + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.3.3.2

Differentiate using the Exponential Rule which states that $\frac{d}{d u_{1}} [a^{u_{1}}]$ is $a^{u_{1}} \ln (a)$ where $a$ = $e$ .

$lim_{x \to \infty} \frac{4 (x^{2} (e^{u_{1}} \frac{d}{d x} [x^{2}]) + e^{x^{2}} \frac{d}{d x} [x^{2}]) + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.3.3.3

Replace all occurrences of $u_{1}$ with $x^{2}$ .

$lim_{x \to \infty} \frac{4 (x^{2} (e^{x^{2}} \frac{d}{d x} [x^{2}]) + e^{x^{2}} \frac{d}{d x} [x^{2}]) + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.3.4

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$lim_{x \to \infty} \frac{4 (x^{2} (e^{x^{2}} (2 x)) + e^{x^{2}} \frac{d}{d x} [x^{2}]) + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.3.5

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$lim_{x \to \infty} \frac{4 (x^{2} (e^{x^{2}} (2 x)) + e^{x^{2}} (2 x)) + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.3.6

Multiply $x^{2}$ by $x$ by adding the exponents.

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Step 4.3.3.6.1

Move $x$ .

$lim_{x \to \infty} \frac{4 (x \cdot x^{2} (e^{x^{2}} \cdot (2)) + e^{x^{2}} (2 x)) + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.3.6.2

Multiply $x$ by $x^{2}$ .

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Step 4.3.3.6.2.1

Raise $x$ to the power of $1$ .

$lim_{x \to \infty} \frac{4 (x^{1} x^{2} (e^{x^{2}} \cdot (2)) + e^{x^{2}} (2 x)) + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.3.6.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$lim_{x \to \infty} \frac{4 (x^{1 + 2} (e^{x^{2}} \cdot (2)) + e^{x^{2}} (2 x)) + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.3.6.3

Add $1$ and $2$ .

$lim_{x \to \infty} \frac{4 (x^{3} (e^{x^{2}} \cdot (2)) + e^{x^{2}} (2 x)) + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.3.7

Move $2$ to the left of $e^{x^{2}}$ .

$lim_{x \to \infty} \frac{4 (x^{3} (2 e^{x^{2}}) + e^{x^{2}} (2 x)) + \frac{d}{d x} [2 e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.4

Evaluate $\frac{d}{d x} [2 e^{x^{2}}]$ .

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Step 4.3.4.1

Since $2$ is constant with respect to $x$ , the derivative of $2 e^{x^{2}}$ with respect to $x$ is $2 \frac{d}{d x} [e^{x^{2}}]$ .

$lim_{x \to \infty} \frac{4 (x^{3} (2 e^{x^{2}}) + e^{x^{2}} (2 x)) + 2 \frac{d}{d x} [e^{x^{2}}]}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.4.2

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = e^{x}$ and $g (x) = x^{2}$ .

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Step 4.3.4.2.1

To apply the Chain Rule, set $u_{2}$ as $x^{2}$ .

$lim_{x \to \infty} \frac{4 (x^{3} (2 e^{x^{2}}) + e^{x^{2}} (2 x)) + 2 (\frac{d}{d u_{2}} [e^{u_{2}}] \frac{d}{d x} [x^{2}])}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.4.2.2

Differentiate using the Exponential Rule which states that $\frac{d}{d u_{2}} [a^{u_{2}}]$ is $a^{u_{2}} \ln (a)$ where $a$ = $e$ .

$lim_{x \to \infty} \frac{4 (x^{3} (2 e^{x^{2}}) + e^{x^{2}} (2 x)) + 2 (e^{u_{2}} \frac{d}{d x} [x^{2}])}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.4.2.3

Replace all occurrences of $u_{2}$ with $x^{2}$ .

$lim_{x \to \infty} \frac{4 (x^{3} (2 e^{x^{2}}) + e^{x^{2}} (2 x)) + 2 (e^{x^{2}} \frac{d}{d x} [x^{2}])}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.4.3

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$lim_{x \to \infty} \frac{4 (x^{3} (2 e^{x^{2}}) + e^{x^{2}} (2 x)) + 2 (e^{x^{2}} (2 x))}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.4.4

Multiply $2$ by $2$ .

$lim_{x \to \infty} \frac{4 (x^{3} (2 e^{x^{2}}) + e^{x^{2}} (2 x)) + 4 e^{x^{2}} x}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.5

Simplify.

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Step 4.3.5.1

Apply the distributive property.

$lim_{x \to \infty} \frac{4 (x^{3} (2 e^{x^{2}})) + 4 (e^{x^{2}} (2 x)) + 4 e^{x^{2}} x}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.5.2

Combine terms.

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Step 4.3.5.2.1

Multiply $2$ by $4$ .

$lim_{x \to \infty} \frac{8 (x^{3} (e^{x^{2}})) + 4 (e^{x^{2}} (2 x)) + 4 e^{x^{2}} x}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.5.2.2

Multiply $2$ by $4$ .

$lim_{x \to \infty} \frac{8 x^{3} e^{x^{2}} + 8 (e^{x^{2}} (x)) + 4 e^{x^{2}} x}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.5.2.3

Add $8 e^{x^{2}} x$ and $4 e^{x^{2}} x$ .

$lim_{x \to \infty} \frac{8 x^{3} e^{x^{2}} + 12 e^{x^{2}} x}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.5.3

Reorder terms.

$lim_{x \to \infty} \frac{8 e^{x^{2}} x^{3} + 12 e^{x^{2}} x}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.5.4

Reorder factors in $8 e^{x^{2}} x^{3} + 12 e^{x^{2}} x$ .

$lim_{x \to \infty} \frac{8 x^{3} e^{x^{2}} + 12 x e^{x^{2}}}{\frac{d}{d x} [12 x^{2}]}$

Step 4.3.6

Since $12$ is constant with respect to $x$ , the derivative of $12 x^{2}$ with respect to $x$ is $12 \frac{d}{d x} [x^{2}]$ .

$lim_{x \to \infty} \frac{8 x^{3} e^{x^{2}} + 12 x e^{x^{2}}}{12 \frac{d}{d x} [x^{2}]}$

Step 4.3.7

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$lim_{x \to \infty} \frac{8 x^{3} e^{x^{2}} + 12 x e^{x^{2}}}{12 (2 x)}$

Step 4.3.8

Multiply $2$ by $12$ .

$lim_{x \to \infty} \frac{8 x^{3} e^{x^{2}} + 12 x e^{x^{2}}}{24 x}$

Step 5

Apply L'Hospital's rule.

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Step 5.1

Evaluate the limit of the numerator and the limit of the denominator.

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Step 5.1.1

Take the limit of the numerator and the limit of the denominator.

$\frac{lim_{x \to \infty} 8 x^{3} e^{x^{2}} + 12 x e^{x^{2}}}{lim_{x \to \infty} 24 x}$

Step 5.1.2

Evaluate the limit of the numerator.

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Step 5.1.2.1

Evaluate the limit.

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Step 5.1.2.1.1

Split the limit using the Sum of Limits Rule on the limit as $x$ approaches $\infty$ .

$\frac{lim_{x \to \infty} 8 x^{3} e^{x^{2}} + lim_{x \to \infty} 12 x e^{x^{2}}}{lim_{x \to \infty} 24 x}$

Step 5.1.2.1.2

Split the limit using the Product of Limits Rule on the limit as $x$ approaches $\infty$ .

$\frac{lim_{x \to \infty} 8 \cdot lim_{x \to \infty} x^{3} \cdot lim_{x \to \infty} e^{x^{2}} + lim_{x \to \infty} 12 x e^{x^{2}}}{lim_{x \to \infty} 24 x}$

Step 5.1.2.1.3

Evaluate the limit of $8$ which is constant as $x$ approaches $\infty$ .

$\frac{8 \cdot lim_{x \to \infty} x^{3} \cdot lim_{x \to \infty} e^{x^{2}} + lim_{x \to \infty} 12 x e^{x^{2}}}{lim_{x \to \infty} 24 x}$

Step 5.1.2.1.4

The limit at infinity of a polynomial whose leading coefficient is positive is infinity.

$\frac{8 \cdot \infty \cdot lim_{x \to \infty} e^{x^{2}} + lim_{x \to \infty} 12 x e^{x^{2}}}{lim_{x \to \infty} 24 x}$

Step 5.1.2.2

Since the exponent $x^{2}$ approaches $\infty$ , the quantity $e^{x^{2}}$ approaches $\infty$ .

$\frac{8 \cdot \infty \cdot \infty + lim_{x \to \infty} 12 x e^{x^{2}}}{lim_{x \to \infty} 24 x}$

Step 5.1.2.3

Evaluate the limit.

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Step 5.1.2.3.1

Split the limit using the Product of Limits Rule on the limit as $x$ approaches $\infty$ .

$\frac{8 \cdot \infty \cdot \infty + lim_{x \to \infty} 12 \cdot lim_{x \to \infty} x \cdot lim_{x \to \infty} e^{x^{2}}}{lim_{x \to \infty} 24 x}$

Step 5.1.2.3.2

Evaluate the limit of $12$ which is constant as $x$ approaches $\infty$ .

$\frac{8 \cdot \infty \cdot \infty + 12 \cdot lim_{x \to \infty} x \cdot lim_{x \to \infty} e^{x^{2}}}{lim_{x \to \infty} 24 x}$

Step 5.1.2.3.3

The limit at infinity of a polynomial whose leading coefficient is positive is infinity.

$\frac{8 \cdot \infty \cdot \infty + 12 \cdot \infty \cdot lim_{x \to \infty} e^{x^{2}}}{lim_{x \to \infty} 24 x}$

Step 5.1.2.4

Since the exponent $x^{2}$ approaches $\infty$ , the quantity $e^{x^{2}}$ approaches $\infty$ .

$\frac{8 \cdot \infty \cdot \infty + 12 \cdot \infty \cdot \infty}{lim_{x \to \infty} 24 x}$

Step 5.1.2.5

Simplify the answer.

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Step 5.1.2.5.1

Simplify each term.

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Step 5.1.2.5.1.1

A non-zero constant times infinity is infinity.

$\frac{\infty \cdot \infty + 12 \cdot \infty \cdot \infty}{lim_{x \to \infty} 24 x}$

Step 5.1.2.5.1.2

Infinity times infinity is infinity.

$\frac{\infty + 12 \cdot \infty \cdot \infty}{lim_{x \to \infty} 24 x}$

Step 5.1.2.5.1.3

A non-zero constant times infinity is infinity.

$\frac{\infty + \infty \cdot \infty}{lim_{x \to \infty} 24 x}$

Step 5.1.2.5.1.4

Infinity times infinity is infinity.

$\frac{\infty + \infty}{lim_{x \to \infty} 24 x}$

Step 5.1.2.5.2

Infinity plus infinity is infinity.

$\frac{\infty}{lim_{x \to \infty} 24 x}$

Step 5.1.3

The limit at infinity of a polynomial whose leading coefficient is positive is infinity.

$\frac{\infty}{\infty}$

Step 5.1.4

Infinity divided by infinity is undefined.

Undefined

$\frac{\infty}{\infty}$

Step 5.2

$lim_{x \to \infty} \frac{8 x^{3} e^{x^{2}} + 12 x e^{x^{2}}}{24 x} = lim_{x \to \infty} \frac{\frac{d}{d x} [8 x^{3} e^{x^{2}} + 12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3

Find the derivative of the numerator and denominator.

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Step 5.3.1

Differentiate the numerator and denominator.

$lim_{x \to \infty} \frac{\frac{d}{d x} [8 x^{3} e^{x^{2}} + 12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.2

By the Sum Rule, the derivative of $8 x^{3} e^{x^{2}} + 12 x e^{x^{2}}$ with respect to $x$ is $\frac{d}{d x} [8 x^{3} e^{x^{2}}] + \frac{d}{d x} [12 x e^{x^{2}}]$ .

$lim_{x \to \infty} \frac{\frac{d}{d x} [8 x^{3} e^{x^{2}}] + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.3

Evaluate $\frac{d}{d x} [8 x^{3} e^{x^{2}}]$ .

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Step 5.3.3.1

Since $8$ is constant with respect to $x$ , the derivative of $8 x^{3} e^{x^{2}}$ with respect to $x$ is $8 \frac{d}{d x} [x^{3} e^{x^{2}}]$ .

$lim_{x \to \infty} \frac{8 \frac{d}{d x} [x^{3} e^{x^{2}}] + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.3.2

Differentiate using the Product Rule which states that $\frac{d}{d x} [f (x) g (x)]$ is $f (x) \frac{d}{d x} [g (x)] + g (x) \frac{d}{d x} [f (x)]$ where $f (x) = x^{3}$ and $g (x) = e^{x^{2}}$ .

$lim_{x \to \infty} \frac{8 (x^{3} \frac{d}{d x} [e^{x^{2}}] + e^{x^{2}} \frac{d}{d x} [x^{3}]) + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.3.3

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = e^{x}$ and $g (x) = x^{2}$ .

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Step 5.3.3.3.1

To apply the Chain Rule, set $u_{1}$ as $x^{2}$ .

$lim_{x \to \infty} \frac{8 (x^{3} (\frac{d}{d u_{1}} [e^{u_{1}}] \frac{d}{d x} [x^{2}]) + e^{x^{2}} \frac{d}{d x} [x^{3}]) + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.3.3.2

Differentiate using the Exponential Rule which states that $\frac{d}{d u_{1}} [a^{u_{1}}]$ is $a^{u_{1}} \ln (a)$ where $a$ = $e$ .

$lim_{x \to \infty} \frac{8 (x^{3} (e^{u_{1}} \frac{d}{d x} [x^{2}]) + e^{x^{2}} \frac{d}{d x} [x^{3}]) + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.3.3.3

Replace all occurrences of $u_{1}$ with $x^{2}$ .

$lim_{x \to \infty} \frac{8 (x^{3} (e^{x^{2}} \frac{d}{d x} [x^{2}]) + e^{x^{2}} \frac{d}{d x} [x^{3}]) + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.3.4

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$lim_{x \to \infty} \frac{8 (x^{3} (e^{x^{2}} (2 x)) + e^{x^{2}} \frac{d}{d x} [x^{3}]) + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.3.5

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 3$ .

$lim_{x \to \infty} \frac{8 (x^{3} (e^{x^{2}} (2 x)) + e^{x^{2}} (3 x^{2})) + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.3.6

Multiply $x^{3}$ by $x$ by adding the exponents.

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Step 5.3.3.6.1

Move $x$ .

$lim_{x \to \infty} \frac{8 (x \cdot x^{3} (e^{x^{2}} \cdot (2)) + e^{x^{2}} (3 x^{2})) + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.3.6.2

Multiply $x$ by $x^{3}$ .

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Step 5.3.3.6.2.1

Raise $x$ to the power of $1$ .

$lim_{x \to \infty} \frac{8 (x^{1} x^{3} (e^{x^{2}} \cdot (2)) + e^{x^{2}} (3 x^{2})) + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.3.6.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$lim_{x \to \infty} \frac{8 (x^{1 + 3} (e^{x^{2}} \cdot (2)) + e^{x^{2}} (3 x^{2})) + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.3.6.3

Add $1$ and $3$ .

$lim_{x \to \infty} \frac{8 (x^{4} (e^{x^{2}} \cdot (2)) + e^{x^{2}} (3 x^{2})) + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.3.7

Move $2$ to the left of $e^{x^{2}}$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + \frac{d}{d x} [12 x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.4

Evaluate $\frac{d}{d x} [12 x e^{x^{2}}]$ .

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Step 5.3.4.1

Since $12$ is constant with respect to $x$ , the derivative of $12 x e^{x^{2}}$ with respect to $x$ is $12 \frac{d}{d x} [x e^{x^{2}}]$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 \frac{d}{d x} [x e^{x^{2}}]}{\frac{d}{d x} [24 x]}$

Step 5.3.4.2

Differentiate using the Product Rule which states that $\frac{d}{d x} [f (x) g (x)]$ is $f (x) \frac{d}{d x} [g (x)] + g (x) \frac{d}{d x} [f (x)]$ where $f (x) = x$ and $g (x) = e^{x^{2}}$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 (x \frac{d}{d x} [e^{x^{2}}] + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [24 x]}$

Step 5.3.4.3

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = e^{x}$ and $g (x) = x^{2}$ .

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Step 5.3.4.3.1

To apply the Chain Rule, set $u_{2}$ as $x^{2}$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 (x (\frac{d}{d u_{2}} [e^{u_{2}}] \frac{d}{d x} [x^{2}]) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [24 x]}$

Step 5.3.4.3.2

Differentiate using the Exponential Rule which states that $\frac{d}{d u_{2}} [a^{u_{2}}]$ is $a^{u_{2}} \ln (a)$ where $a$ = $e$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 (x (e^{u_{2}} \frac{d}{d x} [x^{2}]) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [24 x]}$

Step 5.3.4.3.3

Replace all occurrences of $u_{2}$ with $x^{2}$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 (x (e^{x^{2}} \frac{d}{d x} [x^{2}]) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [24 x]}$

Step 5.3.4.4

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 (x (e^{x^{2}} (2 x)) + e^{x^{2}} \frac{d}{d x} [x])}{\frac{d}{d x} [24 x]}$

Step 5.3.4.5

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 1$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 (x (e^{x^{2}} (2 x)) + e^{x^{2}} \cdot 1)}{\frac{d}{d x} [24 x]}$

Step 5.3.4.6

Raise $x$ to the power of $1$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 (x^{1} x (e^{x^{2}} \cdot (2)) + e^{x^{2}} \cdot 1)}{\frac{d}{d x} [24 x]}$

Step 5.3.4.7

Raise $x$ to the power of $1$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 (x^{1} x^{1} (e^{x^{2}} \cdot (2)) + e^{x^{2}} \cdot 1)}{\frac{d}{d x} [24 x]}$

Step 5.3.4.8

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 (x^{1 + 1} (e^{x^{2}} \cdot (2)) + e^{x^{2}} \cdot 1)}{\frac{d}{d x} [24 x]}$

Step 5.3.4.9

Add $1$ and $1$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 (x^{2} (e^{x^{2}} \cdot (2)) + e^{x^{2}} \cdot 1)}{\frac{d}{d x} [24 x]}$

Step 5.3.4.10

Move $2$ to the left of $e^{x^{2}}$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 (x^{2} (2 \cdot e^{x^{2}}) + e^{x^{2}} \cdot 1)}{\frac{d}{d x} [24 x]}$

Step 5.3.4.11

Multiply $e^{x^{2}}$ by $1$ .

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}}) + e^{x^{2}} (3 x^{2})) + 12 (x^{2} (2 e^{x^{2}}) + e^{x^{2}})}{\frac{d}{d x} [24 x]}$

Step 5.3.5

Simplify.

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Step 5.3.5.1

Apply the distributive property.

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}})) + 8 (e^{x^{2}} (3 x^{2})) + 12 (x^{2} (2 e^{x^{2}}) + e^{x^{2}})}{\frac{d}{d x} [24 x]}$

Step 5.3.5.2

Apply the distributive property.

$lim_{x \to \infty} \frac{8 (x^{4} (2 e^{x^{2}})) + 8 (e^{x^{2}} (3 x^{2})) + 12 (x^{2} (2 e^{x^{2}})) + 12 e^{x^{2}}}{\frac{d}{d x} [24 x]}$

Step 5.3.5.3

Combine terms.

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Step 5.3.5.3.1

Multiply $2$ by $8$ .

$lim_{x \to \infty} \frac{16 (x^{4} (e^{x^{2}})) + 8 (e^{x^{2}} (3 x^{2})) + 12 (x^{2} (2 e^{x^{2}})) + 12 e^{x^{2}}}{\frac{d}{d x} [24 x]}$

Step 5.3.5.3.2

Multiply $3$ by $8$ .

$lim_{x \to \infty} \frac{16 x^{4} e^{x^{2}} + 24 (e^{x^{2}} (x^{2})) + 12 (x^{2} (2 e^{x^{2}})) + 12 e^{x^{2}}}{\frac{d}{d x} [24 x]}$

Step 5.3.5.3.3

Multiply $2$ by $12$ .

$lim_{x \to \infty} \frac{16 x^{4} e^{x^{2}} + 24 e^{x^{2}} x^{2} + 24 (x^{2} (e^{x^{2}})) + 12 e^{x^{2}}}{\frac{d}{d x} [24 x]}$

Step 5.3.5.3.4

Add $24 e^{x^{2}} x^{2}$ and $24 x^{2} e^{x^{2}}$ .

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Step 5.3.5.3.4.1

Move $e^{x^{2}}$ .

$lim_{x \to \infty} \frac{16 x^{4} e^{x^{2}} + 24 x^{2} e^{x^{2}} + 24 x^{2} e^{x^{2}} + 12 e^{x^{2}}}{\frac{d}{d x} [24 x]}$

Step 5.3.5.3.4.2

Add $24 x^{2} e^{x^{2}}$ and $24 x^{2} e^{x^{2}}$ .

$lim_{x \to \infty} \frac{16 x^{4} e^{x^{2}} + 48 x^{2} e^{x^{2}} + 12 e^{x^{2}}}{\frac{d}{d x} [24 x]}$

Step 5.3.5.4

Reorder terms.

$lim_{x \to \infty} \frac{16 e^{x^{2}} x^{4} + 48 e^{x^{2}} x^{2} + 12 e^{x^{2}}}{\frac{d}{d x} [24 x]}$

Step 5.3.5.5

Reorder factors in $16 e^{x^{2}} x^{4} + 48 e^{x^{2}} x^{2} + 12 e^{x^{2}}$ .

$lim_{x \to \infty} \frac{16 x^{4} e^{x^{2}} + 48 x^{2} e^{x^{2}} + 12 e^{x^{2}}}{\frac{d}{d x} [24 x]}$

Step 5.3.6

Since $24$ is constant with respect to $x$ , the derivative of $24 x$ with respect to $x$ is $24 \frac{d}{d x} [x]$ .

$lim_{x \to \infty} \frac{16 x^{4} e^{x^{2}} + 48 x^{2} e^{x^{2}} + 12 e^{x^{2}}}{24 \frac{d}{d x} [x]}$

Step 5.3.7

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 1$ .

$lim_{x \to \infty} \frac{16 x^{4} e^{x^{2}} + 48 x^{2} e^{x^{2}} + 12 e^{x^{2}}}{24 \cdot 1}$

Step 5.3.8

Multiply $24$ by $1$ .

$lim_{x \to \infty} \frac{16 x^{4} e^{x^{2}} + 48 x^{2} e^{x^{2}} + 12 e^{x^{2}}}{24}$

Step 6

Since the function $16 x^{4} e^{x^{2}} + 48 x^{2} e^{x^{2}} + 12 e^{x^{2}}$ approaches $\infty$ , the positive constant $\frac{1}{24}$ times the function also approaches $\infty$ .

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Step 6.1

Consider the limit with the constant multiple $\frac{1}{24}$ removed.

$lim_{x \to \infty} 16 x^{4} e^{x^{2}} + 48 x^{2} e^{x^{2}} + 12 e^{x^{2}}$

Step 6.2

Evaluate the limit.

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Step 6.2.1

Split the limit using the Sum of Limits Rule on the limit as $x$ approaches $\infty$ .

$lim_{x \to \infty} 16 x^{4} e^{x^{2}} + lim_{x \to \infty} 48 x^{2} e^{x^{2}} + lim_{x \to \infty} 12 e^{x^{2}}$

Step 6.2.2

Split the limit using the Product of Limits Rule on the limit as $x$ approaches $\infty$ .

$lim_{x \to \infty} 16 \cdot lim_{x \to \infty} x^{4} \cdot lim_{x \to \infty} e^{x^{2}} + lim_{x \to \infty} 48 x^{2} e^{x^{2}} + lim_{x \to \infty} 12 e^{x^{2}}$

Step 6.2.3

Evaluate the limit of $16$ which is constant as $x$ approaches $\infty$ .

$16 \cdot lim_{x \to \infty} x^{4} \cdot lim_{x \to \infty} e^{x^{2}} + lim_{x \to \infty} 48 x^{2} e^{x^{2}} + lim_{x \to \infty} 12 e^{x^{2}}$

Step 6.2.4

The limit at infinity of a polynomial whose leading coefficient is positive is infinity.

$16 \cdot \infty \cdot lim_{x \to \infty} e^{x^{2}} + lim_{x \to \infty} 48 x^{2} e^{x^{2}} + lim_{x \to \infty} 12 e^{x^{2}}$

Step 6.3

Since the exponent $x^{2}$ approaches $\infty$ , the quantity $e^{x^{2}}$ approaches $\infty$ .

$16 \cdot \infty \cdot \infty + lim_{x \to \infty} 48 x^{2} e^{x^{2}} + lim_{x \to \infty} 12 e^{x^{2}}$

Step 6.4

Evaluate the limit.

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Step 6.4.1

Split the limit using the Product of Limits Rule on the limit as $x$ approaches $\infty$ .

$16 \cdot \infty \cdot \infty + lim_{x \to \infty} 48 \cdot lim_{x \to \infty} x^{2} \cdot lim_{x \to \infty} e^{x^{2}} + lim_{x \to \infty} 12 e^{x^{2}}$

Step 6.4.2

Evaluate the limit of $48$ which is constant as $x$ approaches $\infty$ .

$16 \cdot \infty \cdot \infty + 48 \cdot lim_{x \to \infty} x^{2} \cdot lim_{x \to \infty} e^{x^{2}} + lim_{x \to \infty} 12 e^{x^{2}}$

Step 6.4.3

The limit at infinity of a polynomial whose leading coefficient is positive is infinity.

$16 \cdot \infty \cdot \infty + 48 \cdot \infty \cdot lim_{x \to \infty} e^{x^{2}} + lim_{x \to \infty} 12 e^{x^{2}}$

Step 6.5

Since the exponent $x^{2}$ approaches $\infty$ , the quantity $e^{x^{2}}$ approaches $\infty$ .

$16 \cdot \infty \cdot \infty + 48 \cdot \infty \cdot \infty + lim_{x \to \infty} 12 e^{x^{2}}$

Step 6.6

Since the function $e^{x^{2}}$ approaches $\infty$ , the positive constant $12$ times the function also approaches $\infty$ .

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Step 6.6.1

Consider the limit with the constant multiple $12$ removed.

$16 \cdot \infty \cdot \infty + 48 \cdot \infty \cdot \infty + lim_{x \to \infty} e^{x^{2}}$

Step 6.6.2

Since the exponent $x^{2}$ approaches $\infty$ , the quantity $e^{x^{2}}$ approaches $\infty$ .

$16 \cdot \infty \cdot \infty + 48 \cdot \infty \cdot \infty + \infty$

Step 6.7

Simplify the answer.

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Step 6.7.1

Simplify each term.

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Step 6.7.1.1

A non-zero constant times infinity is infinity.

$\infty \cdot \infty + 48 \cdot \infty \cdot \infty + \infty$

Step 6.7.1.2

Infinity times infinity is infinity.

$\infty + 48 \cdot \infty \cdot \infty + \infty$

Step 6.7.1.3

A non-zero constant times infinity is infinity.

$\infty + \infty \cdot \infty + \infty$

Step 6.7.1.4

Infinity times infinity is infinity.

$\infty + \infty + \infty$

Step 6.7.2

Infinity plus infinity is infinity.

$\infty + \infty$

Step 6.7.3

Infinity plus infinity is infinity.

$\infty$