Calculus Examples

$\frac{x^{2}}{x - 1}$

Step 1

Find the first derivative.

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Step 1.1

Differentiate using the Quotient Rule which states that $\frac{d}{d x} [\frac{f (x)}{g (x)}]$ is $\frac{g (x) \frac{d}{d x} [f (x)] - f (x) \frac{d}{d x} [g (x)]}{{g (x)}^{2}}$ where $f (x) = x^{2}$ and $g (x) = x - 1$ .

$f' (x) = \frac{(x - 1) \frac{d}{d x} (x^{2}) - x^{2} \frac{d}{d x} (x - 1)}{{(x - 1)}^{2}}$

Step 1.2

Differentiate.

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Step 1.2.1

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

$f' (x) = \frac{(x - 1) (2 x) - x^{2} \frac{d}{d x} (x - 1)}{{(x - 1)}^{2}}$

Step 1.2.2

Move $2$ to the left of $x - 1$ .

$f' (x) = \frac{2 \cdot ((x - 1) x) - x^{2} \frac{d}{d x} (x - 1)}{{(x - 1)}^{2}}$

Step 1.2.3

By the Sum Rule, the derivative of $x - 1$ with respect to $x$ is $\frac{d}{d x} [x] + \frac{d}{d x} [- 1]$ .

$f' (x) = \frac{2 (x - 1) x - x^{2} (\frac{d}{d x} (x) + \frac{d}{d x} (- 1))}{{(x - 1)}^{2}}$

Step 1.2.4

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

$f' (x) = \frac{2 (x - 1) x - x^{2} (1 + \frac{d}{d x} (- 1))}{{(x - 1)}^{2}}$

Step 1.2.5

Since $- 1$ is constant with respect to $x$ , the derivative of $- 1$ with respect to $x$ is $0$ .

$f' (x) = \frac{2 (x - 1) x - x^{2} (1 + 0)}{{(x - 1)}^{2}}$

Step 1.2.6

Simplify the expression.

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Step 1.2.6.1

Add $1$ and $0$ .

$f' (x) = \frac{2 (x - 1) x - x^{2} \cdot 1}{{(x - 1)}^{2}}$

Step 1.2.6.2

Multiply $- 1$ by $1$ .

$f' (x) = \frac{2 (x - 1) x - x^{2}}{{(x - 1)}^{2}}$

Step 1.3

Simplify.

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Step 1.3.1

Apply the distributive property.

$f' (x) = \frac{(2 x + 2 \cdot - 1) x - x^{2}}{{(x - 1)}^{2}}$

Step 1.3.2

Apply the distributive property.

$f' (x) = \frac{2 x \cdot x + 2 \cdot (- 1 x) - x^{2}}{{(x - 1)}^{2}}$

Step 1.3.3

Simplify the numerator.

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Step 1.3.3.1

Simplify each term.

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Step 1.3.3.1.1

Multiply $x$ by $x$ by adding the exponents.

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Step 1.3.3.1.1.1

Move $x$ .

$f' (x) = \frac{2 (x \cdot x) + 2 \cdot (- 1 x) - x^{2}}{{(x - 1)}^{2}}$

Step 1.3.3.1.1.2

Multiply $x$ by $x$ .

$f' (x) = \frac{2 x^{2} + 2 \cdot (- 1 x) - x^{2}}{{(x - 1)}^{2}}$

Step 1.3.3.1.2

Multiply $2$ by $- 1$ .

$f' (x) = \frac{2 x^{2} - 2 x - x^{2}}{{(x - 1)}^{2}}$

Step 1.3.3.2

Subtract $x^{2}$ from $2 x^{2}$ .

$f' (x) = \frac{x^{2} - 2 x}{{(x - 1)}^{2}}$

Step 1.3.4

Factor $x$ out of $x^{2} - 2 x$ .

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Step 1.3.4.1

Factor $x$ out of $x^{2}$ .

$f' (x) = \frac{x \cdot x - 2 x}{{(x - 1)}^{2}}$

Step 1.3.4.2

Factor $x$ out of $- 2 x$ .

$f' (x) = \frac{x \cdot x + x \cdot - 2}{{(x - 1)}^{2}}$

Step 1.3.4.3

Factor $x$ out of $x \cdot x + x \cdot - 2$ .

$f' (x) = \frac{x (x - 2)}{{(x - 1)}^{2}}$

Step 2

Find the second derivative.

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Step 2.1

$f'' (x) = \frac{{(x - 1)}^{2} \frac{d}{d x} (x (x - 2)) - x (x - 2) \frac{d}{d x} {(x - 1)}^{2}}{{({(x - 1)}^{2})}^{2}}$

Step 2.2

Multiply the exponents in ${({(x - 1)}^{2})}^{2}$ .

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Step 2.2.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$f'' (x) = \frac{{(x - 1)}^{2} \frac{d}{d x} (x (x - 2)) - x (x - 2) \frac{d}{d x} {(x - 1)}^{2}}{{(x - 1)}^{2 \cdot 2}}$

Step 2.2.2

Multiply $2$ by $2$ .

$f'' (x) = \frac{{(x - 1)}^{2} \frac{d}{d x} (x (x - 2)) - x (x - 2) \frac{d}{d x} {(x - 1)}^{2}}{{(x - 1)}^{4}}$

Step 2.3

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 $g (x) = x - 2$ .

$f'' (x) = \frac{{(x - 1)}^{2} (x \frac{d}{d x} (x - 2) + (x - 2) \frac{d}{d x} (x)) - x (x - 2) \frac{d}{d x} {(x - 1)}^{2}}{{(x - 1)}^{4}}$

Step 2.4

Differentiate.

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Step 2.4.1

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

$f'' (x) = \frac{{(x - 1)}^{2} (x (\frac{d}{d x} (x) + \frac{d}{d x} (- 2)) + (x - 2) \frac{d}{d x} (x)) - x (x - 2) \frac{d}{d x} {(x - 1)}^{2}}{{(x - 1)}^{4}}$

Step 2.4.2

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

$f'' (x) = \frac{{(x - 1)}^{2} (x (1 + \frac{d}{d x} (- 2)) + (x - 2) \frac{d}{d x} (x)) - x (x - 2) \frac{d}{d x} {(x - 1)}^{2}}{{(x - 1)}^{4}}$

Step 2.4.3

Since $- 2$ is constant with respect to $x$ , the derivative of $- 2$ with respect to $x$ is $0$ .

$f'' (x) = \frac{{(x - 1)}^{2} (x (1 + 0) + (x - 2) \frac{d}{d x} (x)) - x (x - 2) \frac{d}{d x} {(x - 1)}^{2}}{{(x - 1)}^{4}}$

Step 2.4.4

Simplify the expression.

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Step 2.4.4.1

Add $1$ and $0$ .

$f'' (x) = \frac{{(x - 1)}^{2} (x \cdot 1 + (x - 2) \frac{d}{d x} (x)) - x (x - 2) \frac{d}{d x} {(x - 1)}^{2}}{{(x - 1)}^{4}}$

Step 2.4.4.2

Multiply $x$ by $1$ .

$f'' (x) = \frac{{(x - 1)}^{2} (x + (x - 2) \frac{d}{d x} (x)) - x (x - 2) \frac{d}{d x} {(x - 1)}^{2}}{{(x - 1)}^{4}}$

Step 2.4.5

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

$f'' (x) = \frac{{(x - 1)}^{2} (x + (x - 2) \cdot 1) - x (x - 2) \frac{d}{d x} {(x - 1)}^{2}}{{(x - 1)}^{4}}$

Step 2.4.6

Simplify by adding terms.

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Step 2.4.6.1

Multiply $x - 2$ by $1$ .

$f'' (x) = \frac{{(x - 1)}^{2} (x + x - 2) - x (x - 2) \frac{d}{d x} {(x - 1)}^{2}}{{(x - 1)}^{4}}$

Step 2.4.6.2

Add $x$ and $x$ .

$f'' (x) = \frac{{(x - 1)}^{2} (2 x - 2) - x (x - 2) \frac{d}{d x} {(x - 1)}^{2}}{{(x - 1)}^{4}}$

Step 2.5

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{2}$ and $g (x) = x - 1$ .

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Step 2.5.1

To apply the Chain Rule, set $u$ as $x - 1$ .

$f'' (x) = \frac{{(x - 1)}^{2} (2 x - 2) - x (x - 2) (\frac{d}{d u} (u^{2}) \frac{d}{d x} (x - 1))}{{(x - 1)}^{4}}$

Step 2.5.2

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

$f'' (x) = \frac{{(x - 1)}^{2} (2 x - 2) - x (x - 2) (2 u \frac{d}{d x} (x - 1))}{{(x - 1)}^{4}}$

Step 2.5.3

Replace all occurrences of $u$ with $x - 1$ .

$f'' (x) = \frac{{(x - 1)}^{2} (2 x - 2) - x (x - 2) (2 (x - 1) \frac{d}{d x} (x - 1))}{{(x - 1)}^{4}}$

Step 2.6

Simplify with factoring out.

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Step 2.6.1

Multiply $2$ by $- 1$ .

$f'' (x) = \frac{{(x - 1)}^{2} (2 x - 2) - 2 x (x - 2) ((x - 1) \frac{d}{d x} (x - 1))}{{(x - 1)}^{4}}$

Step 2.6.2

Factor $x - 1$ out of ${(x - 1)}^{2} (2 x - 2) - 2 x (x - 2) ((x - 1) \frac{d}{d x} [x - 1])$ .

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Step 2.6.2.1

Factor $x - 1$ out of ${(x - 1)}^{2} (2 x - 2)$ .

$f'' (x) = \frac{(x - 1) ((x - 1) (2 x - 2)) - 2 x (x - 2) ((x - 1) \frac{d}{d x} (x - 1))}{{(x - 1)}^{4}}$

Step 2.6.2.2

Factor $x - 1$ out of $- 2 x (x - 2) ((x - 1) \frac{d}{d x} [x - 1])$ .

$f'' (x) = \frac{(x - 1) ((x - 1) (2 x - 2)) + (x - 1) (- 2 x (x - 2) (\frac{d}{d x} (x - 1)))}{{(x - 1)}^{4}}$

Step 2.6.2.3

Factor $x - 1$ out of $(x - 1) ((x - 1) (2 x - 2)) + (x - 1) (- 2 x (x - 2) (\frac{d}{d x} [x - 1]))$ .

$f'' (x) = \frac{(x - 1) ((x - 1) (2 x - 2) - 2 x (x - 2) (\frac{d}{d x} (x - 1)))}{{(x - 1)}^{4}}$

Step 2.7

Cancel the common factors.

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Step 2.7.1

Factor $x - 1$ out of ${(x - 1)}^{4}$ .

$f'' (x) = \frac{(x - 1) ((x - 1) (2 x - 2) - 2 x (x - 2) (\frac{d}{d x} (x - 1)))}{(x - 1) {(x - 1)}^{3}}$

Step 2.7.2

Cancel the common factor.

$f'' (x) = \frac{(x - 1) ((x - 1) (2 x - 2) - 2 x (x - 2) (\frac{d}{d x} (x - 1)))}{(x - 1) {(x - 1)}^{3}}$

Step 2.7.3

Rewrite the expression.

$f'' (x) = \frac{(x - 1) (2 x - 2) - 2 x (x - 2) (\frac{d}{d x} (x - 1))}{{(x - 1)}^{3}}$

Step 2.8

By the Sum Rule, the derivative of $x - 1$ with respect to $x$ is $\frac{d}{d x} [x] + \frac{d}{d x} [- 1]$ .

$f'' (x) = \frac{(x - 1) (2 x - 2) - 2 x (x - 2) (\frac{d}{d x} (x) + \frac{d}{d x} (- 1))}{{(x - 1)}^{3}}$

Step 2.9

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

$f'' (x) = \frac{(x - 1) (2 x - 2) - 2 x (x - 2) (1 + \frac{d}{d x} (- 1))}{{(x - 1)}^{3}}$

Step 2.10

Since $- 1$ is constant with respect to $x$ , the derivative of $- 1$ with respect to $x$ is $0$ .

$f'' (x) = \frac{(x - 1) (2 x - 2) - 2 x (x - 2) (1 + 0)}{{(x - 1)}^{3}}$

Step 2.11

Simplify the expression.

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Step 2.11.1

Add $1$ and $0$ .

$f'' (x) = \frac{(x - 1) (2 x - 2) - 2 x (x - 2) \cdot 1}{{(x - 1)}^{3}}$

Step 2.11.2

Multiply $- 2$ by $1$ .

$f'' (x) = \frac{(x - 1) (2 x - 2) - 2 x (x - 2)}{{(x - 1)}^{3}}$

Step 2.12

Simplify.

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Step 2.12.1

Apply the distributive property.

$f'' (x) = \frac{(x - 1) (2 x - 2) - 2 x \cdot x - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2

Simplify the numerator.

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Step 2.12.2.1

Simplify each term.

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Step 2.12.2.1.1

Expand $(x - 1) (2 x - 2)$ using the FOIL Method.

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Step 2.12.2.1.1.1

Apply the distributive property.

$f'' (x) = \frac{x (2 x - 2) - 1 (2 x - 2) - 2 x \cdot x - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2.1.1.2

Apply the distributive property.

$f'' (x) = \frac{x (2 x) + x \cdot - 2 - 1 (2 x - 2) - 2 x \cdot x - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2.1.1.3

Apply the distributive property.

$f'' (x) = \frac{x (2 x) + x \cdot - 2 - 1 (2 x) - 1 \cdot - 2 - 2 x \cdot x - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2.1.2

Simplify and combine like terms.

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Step 2.12.2.1.2.1

Simplify each term.

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Step 2.12.2.1.2.1.1

Rewrite using the commutative property of multiplication.

$f'' (x) = \frac{2 x \cdot x + x \cdot - 2 - 1 (2 x) - 1 \cdot - 2 - 2 x \cdot x - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2.1.2.1.2

Multiply $x$ by $x$ by adding the exponents.

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Step 2.12.2.1.2.1.2.1

Move $x$ .

$f'' (x) = \frac{2 (x \cdot x) + x \cdot - 2 - 1 (2 x) - 1 \cdot - 2 - 2 x \cdot x - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2.1.2.1.2.2

Multiply $x$ by $x$ .

$f'' (x) = \frac{2 x^{2} + x \cdot - 2 - 1 (2 x) - 1 \cdot - 2 - 2 x \cdot x - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2.1.2.1.3

Move $- 2$ to the left of $x$ .

$f'' (x) = \frac{2 x^{2} - 2 \cdot x - 1 (2 x) - 1 \cdot - 2 - 2 x \cdot x - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2.1.2.1.4

Multiply $2$ by $- 1$ .

$f'' (x) = \frac{2 x^{2} - 2 x - 2 x - 1 \cdot - 2 - 2 x \cdot x - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2.1.2.1.5

Multiply $- 1$ by $- 2$ .

$f'' (x) = \frac{2 x^{2} - 2 x - 2 x + 2 - 2 x \cdot x - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2.1.2.2

Subtract $2 x$ from $- 2 x$ .

$f'' (x) = \frac{2 x^{2} - 4 x + 2 - 2 x \cdot x - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2.1.3

Multiply $x$ by $x$ by adding the exponents.

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Step 2.12.2.1.3.1

Move $x$ .

$f'' (x) = \frac{2 x^{2} - 4 x + 2 - 2 (x \cdot x) - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2.1.3.2

Multiply $x$ by $x$ .

$f'' (x) = \frac{2 x^{2} - 4 x + 2 - 2 x^{2} - 2 x \cdot - 2}{{(x - 1)}^{3}}$

Step 2.12.2.1.4

Multiply $- 2$ by $- 2$ .

$f'' (x) = \frac{2 x^{2} - 4 x + 2 - 2 x^{2} + 4 x}{{(x - 1)}^{3}}$

Step 2.12.2.2

Combine the opposite terms in $2 x^{2} - 4 x + 2 - 2 x^{2} + 4 x$ .

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Step 2.12.2.2.1

Subtract $2 x^{2}$ from $2 x^{2}$ .

$f'' (x) = \frac{- 4 x + 2 + 0 + 4 x}{{(x - 1)}^{3}}$

Step 2.12.2.2.2

Add $- 4 x + 2$ and $0$ .

$f'' (x) = \frac{- 4 x + 2 + 4 x}{{(x - 1)}^{3}}$

Step 2.12.2.2.3

Add $- 4 x$ and $4 x$ .

$f'' (x) = \frac{0 + 2}{{(x - 1)}^{3}}$

Step 2.12.2.2.4

Add $0$ and $2$ .

$f'' (x) = \frac{2}{{(x - 1)}^{3}}$