Calculus Examples

$y = \frac{x}{2 x + 1}$

Step 1

Differentiate both sides of the equation.

$\frac{d}{d x} (y) = \frac{d}{d x} (\frac{x}{2 x + 1})$

Step 2

The derivative of $y$ with respect to $x$ is $y'$ .

$y'$

Step 3

Differentiate the right side of the equation.

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Step 3.1

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 $f (x) = x$ and $g (x) = 2 x + 1$ .

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

Step 3.2

Differentiate.

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Step 3.2.1

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

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

Step 3.2.2

Multiply $2 x + 1$ by $1$ .

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

Step 3.2.3

By the Sum Rule, the derivative of $2 x + 1$ with respect to $x$ is $\frac{d}{d x} [2 x] + \frac{d}{d x} [1]$ .

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

Step 3.2.4

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

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

Step 3.2.5

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

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

Step 3.2.6

Multiply $2$ by $1$ .

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

Step 3.2.7

Since $1$ is constant with respect to $x$ , the derivative of $1$ with respect to $x$ is $0$ .

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

Step 3.2.8

Simplify by adding terms.

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Step 3.2.8.1

Add $2$ and $0$ .

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

Step 3.2.8.2

Multiply $2$ by $- 1$ .

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

Step 3.2.8.3

Subtract $2 x$ from $2 x$ .

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

Step 3.2.8.4

Add $0$ and $1$ .

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

Step 4

Reform the equation by setting the left side equal to the right side.

$y' = \frac{1}{{(2 x + 1)}^{2}}$

Step 5

Replace $y'$ with $\frac{d y}{d x}$ .

$\frac{d y}{d x} = \frac{1}{{(2 x + 1)}^{2}}$