Calculus Examples

$\frac{100 x}{x + 9}$

Step 1

Since $100$ is constant with respect to $x$ , the derivative of $\frac{100 x}{x + 9}$ with respect to $x$ is $100 \frac{d}{d x} [\frac{x}{x + 9}]$ .

$100 \frac{d}{d x} [\frac{x}{x + 9}]$

Step 2

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 $f (x) = x$ and $g (x) = x + 9$ .

$100 \frac{(x + 9) \frac{d}{d x} [x] - x \frac{d}{d x} [x + 9]}{{(x + 9)}^{2}}$

Step 3

Differentiate.

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Step 3.1

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

$100 \frac{(x + 9) \cdot 1 - x \frac{d}{d x} [x + 9]}{{(x + 9)}^{2}}$

Step 3.2

Multiply $x + 9$ by $1$ .

$100 \frac{x + 9 - x \frac{d}{d x} [x + 9]}{{(x + 9)}^{2}}$

Step 3.3

By the Sum Rule, the derivative of $x + 9$ with respect to $x$ is $\frac{d}{d x} [x] + \frac{d}{d x} [9]$ .

$100 \frac{x + 9 - x (\frac{d}{d x} [x] + \frac{d}{d x} [9])}{{(x + 9)}^{2}}$

Step 3.4

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

$100 \frac{x + 9 - x (1 + \frac{d}{d x} [9])}{{(x + 9)}^{2}}$

Step 3.5

Since $9$ is constant with respect to $x$ , the derivative of $9$ with respect to $x$ is $0$ .

$100 \frac{x + 9 - x (1 + 0)}{{(x + 9)}^{2}}$

Step 3.6

Simplify terms.

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Step 3.6.1

Add $1$ and $0$ .

$100 \frac{x + 9 - x \cdot 1}{{(x + 9)}^{2}}$

Step 3.6.2

Multiply $- 1$ by $1$ .

$100 \frac{x + 9 - x}{{(x + 9)}^{2}}$

Step 3.6.3

Subtract $x$ from $x$ .

$100 \frac{0 + 9}{{(x + 9)}^{2}}$

Step 3.6.4

Add $0$ and $9$ .

$100 \frac{9}{{(x + 9)}^{2}}$

Step 3.6.5

Combine $100$ and $\frac{9}{{(x + 9)}^{2}}$ .

$\frac{100 \cdot 9}{{(x + 9)}^{2}}$

Step 3.6.6

Multiply $100$ by $9$ .

$\frac{900}{{(x + 9)}^{2}}$