Calculus Examples

$f (x) = x \sqrt{x - x^{8}}$

Step 1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{x - x^{8}}$ as ${(x - x^{8})}^{\frac{1}{2}}$ .

$\frac{d}{d x} [x {(x - x^{8})}^{\frac{1}{2}}]$

Step 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 $g (x) = {(x - x^{8})}^{\frac{1}{2}}$ .

$x \frac{d}{d x} [{(x - x^{8})}^{\frac{1}{2}}] + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 3

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{\frac{1}{2}}$ and $g (x) = x - x^{8}$ .

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Step 3.1

To apply the Chain Rule, set $u$ as $x - x^{8}$ .

$x (\frac{d}{d u} [u^{\frac{1}{2}}] \frac{d}{d x} [x - x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 3.2

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

$x (\frac{1}{2} u^{\frac{1}{2} - 1} \frac{d}{d x} [x - x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 3.3

Replace all occurrences of $u$ with $x - x^{8}$ .

$x (\frac{1}{2} {(x - x^{8})}^{\frac{1}{2} - 1} \frac{d}{d x} [x - x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 4

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$x (\frac{1}{2} {(x - x^{8})}^{\frac{1}{2} - 1 \cdot \frac{2}{2}} \frac{d}{d x} [x - x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 5

Combine $- 1$ and $\frac{2}{2}$ .

$x (\frac{1}{2} {(x - x^{8})}^{\frac{1}{2} + \frac{- 1 \cdot 2}{2}} \frac{d}{d x} [x - x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 6

Combine the numerators over the common denominator.

$x (\frac{1}{2} {(x - x^{8})}^{\frac{1 - 1 \cdot 2}{2}} \frac{d}{d x} [x - x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 7

Simplify the numerator.

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Step 7.1

Multiply $- 1$ by $2$ .

$x (\frac{1}{2} {(x - x^{8})}^{\frac{1 - 2}{2}} \frac{d}{d x} [x - x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 7.2

Subtract $2$ from $1$ .

$x (\frac{1}{2} {(x - x^{8})}^{\frac{- 1}{2}} \frac{d}{d x} [x - x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 8

Combine fractions.

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Step 8.1

Move the negative in front of the fraction.

$x (\frac{1}{2} {(x - x^{8})}^{- \frac{1}{2}} \frac{d}{d x} [x - x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 8.2

Combine $\frac{1}{2}$ and ${(x - x^{8})}^{- \frac{1}{2}}$ .

$x (\frac{{(x - x^{8})}^{- \frac{1}{2}}}{2} \frac{d}{d x} [x - x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 8.3

Move ${(x - x^{8})}^{- \frac{1}{2}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$x (\frac{1}{2 {(x - x^{8})}^{\frac{1}{2}}} \frac{d}{d x} [x - x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 8.4

Combine $\frac{1}{2 {(x - x^{8})}^{\frac{1}{2}}}$ and $x$ .

$\frac{x}{2 {(x - x^{8})}^{\frac{1}{2}}} \frac{d}{d x} [x - x^{8}] + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 9

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

$\frac{x}{2 {(x - x^{8})}^{\frac{1}{2}}} (\frac{d}{d x} [x] + \frac{d}{d x} [- x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 10

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

$\frac{x}{2 {(x - x^{8})}^{\frac{1}{2}}} (1 + \frac{d}{d x} [- x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 11

Since $- 1$ is constant with respect to $x$ , the derivative of $- x^{8}$ with respect to $x$ is $- \frac{d}{d x} [x^{8}]$ .

$\frac{x}{2 {(x - x^{8})}^{\frac{1}{2}}} (1 - \frac{d}{d x} [x^{8}]) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 12

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 8$ .

$\frac{x}{2 {(x - x^{8})}^{\frac{1}{2}}} (1 - (8 x^{7})) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 13

Multiply $8$ by $- 1$ .

$\frac{x}{2 {(x - x^{8})}^{\frac{1}{2}}} (1 - 8 x^{7}) + {(x - x^{8})}^{\frac{1}{2}} \frac{d}{d x} [x]$

Step 14

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

$\frac{x}{2 {(x - x^{8})}^{\frac{1}{2}}} (1 - 8 x^{7}) + {(x - x^{8})}^{\frac{1}{2}} \cdot 1$

Step 15

Multiply ${(x - x^{8})}^{\frac{1}{2}}$ by $1$ .

$\frac{x}{2 {(x - x^{8})}^{\frac{1}{2}}} (1 - 8 x^{7}) + {(x - x^{8})}^{\frac{1}{2}}$

Step 16

Simplify.

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Step 16.1

Reorder terms.

$(1 - 8 x^{7}) \frac{x}{2 {(x - x^{8})}^{\frac{1}{2}}} + {(x - x^{8})}^{\frac{1}{2}}$

Step 16.2

Multiply $1 - 8 x^{7}$ by $\frac{x}{2 {(x - x^{8})}^{\frac{1}{2}}}$ .

$\frac{(1 - 8 x^{7}) x}{2 {(x - x^{8})}^{\frac{1}{2}}} + {(x - x^{8})}^{\frac{1}{2}}$

Step 16.3

To write ${(x - x^{8})}^{\frac{1}{2}}$ as a fraction with a common denominator, multiply by $\frac{2 {(x - x^{8})}^{\frac{1}{2}}}{2 {(x - x^{8})}^{\frac{1}{2}}}$ .

$\frac{(1 - 8 x^{7}) x}{2 {(x - x^{8})}^{\frac{1}{2}}} + {(x - x^{8})}^{\frac{1}{2}} \cdot \frac{2 {(x - x^{8})}^{\frac{1}{2}}}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.4

Combine ${(x - x^{8})}^{\frac{1}{2}}$ and $\frac{2 {(x - x^{8})}^{\frac{1}{2}}}{2 {(x - x^{8})}^{\frac{1}{2}}}$ .

$\frac{(1 - 8 x^{7}) x}{2 {(x - x^{8})}^{\frac{1}{2}}} + \frac{{(x - x^{8})}^{\frac{1}{2}} (2 {(x - x^{8})}^{\frac{1}{2}})}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.5

Combine the numerators over the common denominator.

$\frac{(1 - 8 x^{7}) x + {(x - x^{8})}^{\frac{1}{2}} (2 {(x - x^{8})}^{\frac{1}{2}})}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6

Simplify the numerator.

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Step 16.6.1

Apply the distributive property.

$\frac{1 x - 8 x^{7} x + {(x - x^{8})}^{\frac{1}{2}} \cdot 2 {(x - x^{8})}^{\frac{1}{2}}}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.2

Multiply $x$ by $1$ .

$\frac{x - 8 x^{7} x + {(x - x^{8})}^{\frac{1}{2}} \cdot 2 {(x - x^{8})}^{\frac{1}{2}}}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.3

Multiply $x^{7}$ by $x$ by adding the exponents.

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Step 16.6.3.1

Move $x$ .

$\frac{x - 8 (x \cdot x^{7}) + {(x - x^{8})}^{\frac{1}{2}} \cdot 2 {(x - x^{8})}^{\frac{1}{2}}}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.3.2

Multiply $x$ by $x^{7}$ .

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Step 16.6.3.2.1

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

$\frac{x - 8 (x^{1} x^{7}) + {(x - x^{8})}^{\frac{1}{2}} \cdot 2 {(x - x^{8})}^{\frac{1}{2}}}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.3.2.2

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

$\frac{x - 8 x^{1 + 7} + {(x - x^{8})}^{\frac{1}{2}} \cdot 2 {(x - x^{8})}^{\frac{1}{2}}}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.3.3

Add $1$ and $7$ .

$\frac{x - 8 x^{8} + {(x - x^{8})}^{\frac{1}{2}} \cdot 2 {(x - x^{8})}^{\frac{1}{2}}}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.4

Multiply ${(x - x^{8})}^{\frac{1}{2}}$ by ${(x - x^{8})}^{\frac{1}{2}}$ by adding the exponents.

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Step 16.6.4.1

Move ${(x - x^{8})}^{\frac{1}{2}}$ .

$\frac{x - 8 x^{8} + {(x - x^{8})}^{\frac{1}{2}} {(x - x^{8})}^{\frac{1}{2}} \cdot 2}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.4.2

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

$\frac{x - 8 x^{8} + {(x - x^{8})}^{\frac{1}{2} + \frac{1}{2}} \cdot 2}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.4.3

Combine the numerators over the common denominator.

$\frac{x - 8 x^{8} + {(x - x^{8})}^{\frac{1 + 1}{2}} \cdot 2}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.4.4

Add $1$ and $1$ .

$\frac{x - 8 x^{8} + {(x - x^{8})}^{\frac{2}{2}} \cdot 2}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.4.5

Divide $2$ by $2$ .

$\frac{x - 8 x^{8} + {(x - x^{8})}^{1} \cdot 2}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.5

Simplify ${(x - x^{8})}^{1} \cdot 2$ .

$\frac{x - 8 x^{8} + (x - x^{8}) \cdot 2}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.6

Apply the distributive property.

$\frac{x - 8 x^{8} + x \cdot 2 - x^{8} \cdot 2}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.7

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

$\frac{x - 8 x^{8} + 2 \cdot x - x^{8} \cdot 2}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.8

Multiply $2$ by $- 1$ .

$\frac{x - 8 x^{8} + 2 \cdot x - 2 x^{8}}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.9

Add $x$ and $2 x$ .

$\frac{- 8 x^{8} + 3 x - 2 x^{8}}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.10

Subtract $2 x^{8}$ from $- 8 x^{8}$ .

$\frac{- 10 x^{8} + 3 x}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.11

Factor $x$ out of $- 10 x^{8} + 3 x$ .

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Step 16.6.11.1

Factor $x$ out of $- 10 x^{8}$ .

$\frac{x (- 10 x^{7}) + 3 x}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.11.2

Factor $x$ out of $3 x$ .

$\frac{x (- 10 x^{7}) + x \cdot 3}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.6.11.3

Factor $x$ out of $x (- 10 x^{7}) + x \cdot 3$ .

$\frac{x (- 10 x^{7} + 3)}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.7

Factor $- 1$ out of $- 10 x^{7}$ .

$\frac{x (- (10 x^{7}) + 3)}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.8

Rewrite $3$ as $- 1 (- 3)$ .

$\frac{x (- (10 x^{7}) - 1 (- 3))}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.9

Factor $- 1$ out of $- (10 x^{7}) - 1 (- 3)$ .

$\frac{x (- (10 x^{7} - 3))}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.10

Rewrite $- (10 x^{7} - 3)$ as $- 1 (10 x^{7} - 3)$ .

$\frac{x (- 1 (10 x^{7} - 3))}{2 {(x - x^{8})}^{\frac{1}{2}}}$

Step 16.11

Move the negative in front of the fraction.

$- \frac{x (10 x^{7} - 3)}{2 {(x - x^{8})}^{\frac{1}{2}}}$