Calculus Examples

$y = \frac{x^{5}}{4 - x^{4}}$

Step 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 $f (x) = x^{5}$ and $g (x) = 4 - x^{4}$ .

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

Step 2

Differentiate.

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Step 2.1

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 5$ .

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

Step 2.2

Move $5$ to the left of $4 - x^{4}$ .

$\frac{5 \cdot (4 - x^{4}) x^{4} - x^{5} \frac{d}{d x} [4 - x^{4}]}{{(4 - x^{4})}^{2}}$

Step 2.3

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

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

Step 2.4

Since $4$ is constant with respect to $x$ , the derivative of $4$ with respect to $x$ is $0$ .

$\frac{5 (4 - x^{4}) x^{4} - x^{5} (0 + \frac{d}{d x} [- x^{4}])}{{(4 - x^{4})}^{2}}$

Step 2.5

Add $0$ and $\frac{d}{d x} [- x^{4}]$ .

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

Step 2.6

Since $- 1$ is constant with respect to $x$ , the derivative of $- x^{4}$ with respect to $x$ is $- \frac{d}{d x} [x^{4}]$ .

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

Step 2.7

Multiply.

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Step 2.7.1

Multiply $- 1$ by $- 1$ .

$\frac{5 (4 - x^{4}) x^{4} + 1 x^{5} \frac{d}{d x} [x^{4}]}{{(4 - x^{4})}^{2}}$

Step 2.7.2

Multiply $x^{5}$ by $1$ .

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

Step 2.8

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

$\frac{5 (4 - x^{4}) x^{4} + x^{5} (4 x^{3})}{{(4 - x^{4})}^{2}}$

Step 3

Multiply $x^{5}$ by $x^{3}$ by adding the exponents.

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Step 3.1

Move $x^{3}$ .

$\frac{5 (4 - x^{4}) x^{4} + x^{3} x^{5} \cdot 4}{{(4 - x^{4})}^{2}}$

Step 3.2

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

$\frac{5 (4 - x^{4}) x^{4} + x^{3 + 5} \cdot 4}{{(4 - x^{4})}^{2}}$

Step 3.3

Add $3$ and $5$ .

$\frac{5 (4 - x^{4}) x^{4} + x^{8} \cdot 4}{{(4 - x^{4})}^{2}}$

Step 4

Move $4$ to the left of $x^{8}$ .

$\frac{5 (4 - x^{4}) x^{4} + 4 \cdot x^{8}}{{(4 - x^{4})}^{2}}$

Step 5

Simplify.

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Step 5.1

Apply the distributive property.

$\frac{(5 \cdot 4 + 5 (- x^{4})) x^{4} + 4 x^{8}}{{(4 - x^{4})}^{2}}$

Step 5.2

Apply the distributive property.

$\frac{5 \cdot 4 x^{4} + 5 (- x^{4}) x^{4} + 4 x^{8}}{{(4 - x^{4})}^{2}}$

Step 5.3

Simplify the numerator.

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Step 5.3.1

Simplify each term.

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Step 5.3.1.1

Multiply $5$ by $4$ .

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

Step 5.3.1.2

Multiply $x^{4}$ by $x^{4}$ by adding the exponents.

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Step 5.3.1.2.1

Move $x^{4}$ .

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

Step 5.3.1.2.2

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

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

Step 5.3.1.2.3

Add $4$ and $4$ .

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

Step 5.3.1.3

Multiply $- 1$ by $5$ .

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

Step 5.3.2

Add $- 5 x^{8}$ and $4 x^{8}$ .

$\frac{20 x^{4} - x^{8}}{{(4 - x^{4})}^{2}}$

Step 5.4

Reorder terms.

$\frac{- x^{8} + 20 x^{4}}{{(- x^{4} + 4)}^{2}}$