Precalculus Examples

$f (x) = \frac{1}{20 x^{3}}$

Step 1

Since $\frac{1}{20}$ is constant with respect to $x$ , the derivative of $\frac{1}{20 x^{3}}$ with respect to $x$ is $\frac{1}{20} \frac{d}{d x} [\frac{1}{x^{3}}]$ .

$\frac{1}{20} \frac{d}{d x} [\frac{1}{x^{3}}]$

Step 2

Apply basic rules of exponents.

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Step 2.1

Rewrite $\frac{1}{x^{3}}$ as ${(x^{3})}^{- 1}$ .

$\frac{1}{20} \frac{d}{d x} [{(x^{3})}^{- 1}]$

Step 2.2

Multiply the exponents in ${(x^{3})}^{- 1}$ .

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Step 2.2.1

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

$\frac{1}{20} \frac{d}{d x} [x^{3 \cdot - 1}]$

Step 2.2.2

Multiply $3$ by $- 1$ .

$\frac{1}{20} \frac{d}{d x} [x^{- 3}]$

Step 3

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

$\frac{1}{20} (- 3 x^{- 4})$

Step 4

Combine fractions.

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Step 4.1

Combine $- 3$ and $\frac{1}{20}$ .

$\frac{- 3}{20} x^{- 4}$

Step 4.2

Combine $\frac{- 3}{20}$ and $x^{- 4}$ .

$\frac{- 3 x^{- 4}}{20}$

Step 4.3

Simplify the expression.

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Step 4.3.1

Move $x^{- 4}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$\frac{- 3}{20 x^{4}}$

Step 4.3.2

Move the negative in front of the fraction.

$- \frac{3}{20 x^{4}}$