Calculus Examples

$y = {(x^{8} - 5 x^{4} + 2 x)}^{- 6}$

Step 1

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{- 6}$ and $g (x) = x^{8} - 5 x^{4} + 2 x$ .

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Step 1.1

To apply the Chain Rule, set $u$ as $x^{8} - 5 x^{4} + 2 x$ .

$\frac{d}{d u} [u^{- 6}] \frac{d}{d x} [x^{8} - 5 x^{4} + 2 x]$

Step 1.2

Differentiate using the Power Rule which states that $\frac{d}{d u} [u^{n}]$ is $n u^{n - 1}$ where $n = - 6$ .

$- 6 u^{- 7} \frac{d}{d x} [x^{8} - 5 x^{4} + 2 x]$

Step 1.3

Replace all occurrences of $u$ with $x^{8} - 5 x^{4} + 2 x$ .

$- 6 {(x^{8} - 5 x^{4} + 2 x)}^{- 7} \frac{d}{d x} [x^{8} - 5 x^{4} + 2 x]$

Step 2

Differentiate.

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Step 2.1

By the Sum Rule, the derivative of $x^{8} - 5 x^{4} + 2 x$ with respect to $x$ is $\frac{d}{d x} [x^{8}] + \frac{d}{d x} [- 5 x^{4}] + \frac{d}{d x} [2 x]$ .

$- 6 {(x^{8} - 5 x^{4} + 2 x)}^{- 7} (\frac{d}{d x} [x^{8}] + \frac{d}{d x} [- 5 x^{4}] + \frac{d}{d x} [2 x])$

Step 2.2

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

$- 6 {(x^{8} - 5 x^{4} + 2 x)}^{- 7} (8 x^{7} + \frac{d}{d x} [- 5 x^{4}] + \frac{d}{d x} [2 x])$

Step 2.3

Since $- 5$ is constant with respect to $x$ , the derivative of $- 5 x^{4}$ with respect to $x$ is $- 5 \frac{d}{d x} [x^{4}]$ .

$- 6 {(x^{8} - 5 x^{4} + 2 x)}^{- 7} (8 x^{7} - 5 \frac{d}{d x} [x^{4}] + \frac{d}{d x} [2 x])$

Step 2.4

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 4$ .

$- 6 {(x^{8} - 5 x^{4} + 2 x)}^{- 7} (8 x^{7} - 5 (4 x^{3}) + \frac{d}{d x} [2 x])$

Step 2.5

Multiply $4$ by $- 5$ .

$- 6 {(x^{8} - 5 x^{4} + 2 x)}^{- 7} (8 x^{7} - 20 x^{3} + \frac{d}{d x} [2 x])$

Step 2.6

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

$- 6 {(x^{8} - 5 x^{4} + 2 x)}^{- 7} (8 x^{7} - 20 x^{3} + 2 \frac{d}{d x} [x])$

Step 2.7

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

$- 6 {(x^{8} - 5 x^{4} + 2 x)}^{- 7} (8 x^{7} - 20 x^{3} + 2 \cdot 1)$

Step 2.8

Multiply $2$ by $1$ .

$- 6 {(x^{8} - 5 x^{4} + 2 x)}^{- 7} (8 x^{7} - 20 x^{3} + 2)$

Step 3

Rewrite the expression using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$- 6 \frac{1}{{(x^{8} - 5 x^{4} + 2 x)}^{7}} (8 x^{7} - 20 x^{3} + 2)$

Step 4

Simplify.

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Step 4.1

Combine terms.

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Step 4.1.1

Combine $- 6$ and $\frac{1}{{(x^{8} - 5 x^{4} + 2 x)}^{7}}$ .

$\frac{- 6}{{(x^{8} - 5 x^{4} + 2 x)}^{7}} (8 x^{7} - 20 x^{3} + 2)$

Step 4.1.2

Move the negative in front of the fraction.

$- \frac{6}{{(x^{8} - 5 x^{4} + 2 x)}^{7}} (8 x^{7} - 20 x^{3} + 2)$

Step 4.2

Reorder the factors of $- \frac{6}{{(x^{8} - 5 x^{4} + 2 x)}^{7}} (8 x^{7} - 20 x^{3} + 2)$ .

$- (8 x^{7} - 20 x^{3} + 2) \frac{6}{{(x^{8} - 5 x^{4} + 2 x)}^{7}}$