Calculus Examples

$y = \frac{2 x^{2} - 1}{5 x + 2}$

Step 1

Differentiate both sides of the equation.

$\frac{d}{d x} (y) = \frac{d}{d x} (\frac{2 x^{2} - 1}{5 x + 2})$

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 $f (x) = 2 x^{2} - 1$ and $g (x) = 5 x + 2$ .

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

Step 3.2

Differentiate.

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Step 3.2.1

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

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

Step 3.2.2

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

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

Step 3.2.3

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

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

Step 3.2.4

Multiply $2$ by $2$ .

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

Step 3.2.5

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

$\frac{(5 x + 2) (4 x + 0) - (2 x^{2} - 1) \frac{d}{d x} [5 x + 2]}{{(5 x + 2)}^{2}}$

Step 3.2.6

Simplify the expression.

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Step 3.2.6.1

Add $4 x$ and $0$ .

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

Step 3.2.6.2

Move $4$ to the left of $5 x + 2$ .

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

Step 3.2.7

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

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

Step 3.2.8

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

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

Step 3.2.9

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

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

Step 3.2.10

Multiply $5$ by $1$ .

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

Step 3.2.11

Since $2$ is constant with respect to $x$ , the derivative of $2$ with respect to $x$ is $0$ .

$\frac{4 (5 x + 2) x - (2 x^{2} - 1) (5 + 0)}{{(5 x + 2)}^{2}}$

Step 3.2.12

Simplify the expression.

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Step 3.2.12.1

Add $5$ and $0$ .

$\frac{4 (5 x + 2) x - (2 x^{2} - 1) \cdot 5}{{(5 x + 2)}^{2}}$

Step 3.2.12.2

Multiply $5$ by $- 1$ .

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

Step 3.3

Simplify.

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Step 3.3.1

Apply the distributive property.

$\frac{(4 (5 x) + 4 \cdot 2) x - 5 (2 x^{2} - 1)}{{(5 x + 2)}^{2}}$

Step 3.3.2

Apply the distributive property.

$\frac{4 (5 x) x + 4 \cdot 2 x - 5 (2 x^{2} - 1)}{{(5 x + 2)}^{2}}$

Step 3.3.3

Apply the distributive property.

$\frac{4 (5 x) x + 4 \cdot 2 x - 5 (2 x^{2}) - 5 \cdot - 1}{{(5 x + 2)}^{2}}$

Step 3.3.4

Simplify the numerator.

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Step 3.3.4.1

Simplify each term.

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Step 3.3.4.1.1

Multiply $x$ by $x$ by adding the exponents.

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Step 3.3.4.1.1.1

Move $x$ .

$\frac{4 (5 (x \cdot x)) + 4 \cdot 2 x - 5 (2 x^{2}) - 5 \cdot - 1}{{(5 x + 2)}^{2}}$

Step 3.3.4.1.1.2

Multiply $x$ by $x$ .

$\frac{4 (5 x^{2}) + 4 \cdot 2 x - 5 (2 x^{2}) - 5 \cdot - 1}{{(5 x + 2)}^{2}}$

Step 3.3.4.1.2

Multiply $5$ by $4$ .

$\frac{20 x^{2} + 4 \cdot 2 x - 5 (2 x^{2}) - 5 \cdot - 1}{{(5 x + 2)}^{2}}$

Step 3.3.4.1.3

Multiply $4$ by $2$ .

$\frac{20 x^{2} + 8 x - 5 (2 x^{2}) - 5 \cdot - 1}{{(5 x + 2)}^{2}}$

Step 3.3.4.1.4

Multiply $2$ by $- 5$ .

$\frac{20 x^{2} + 8 x - 10 x^{2} - 5 \cdot - 1}{{(5 x + 2)}^{2}}$

Step 3.3.4.1.5

Multiply $- 5$ by $- 1$ .

$\frac{20 x^{2} + 8 x - 10 x^{2} + 5}{{(5 x + 2)}^{2}}$

Step 3.3.4.2

Subtract $10 x^{2}$ from $20 x^{2}$ .

$\frac{10 x^{2} + 8 x + 5}{{(5 x + 2)}^{2}}$

Step 4

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

$y' = \frac{10 x^{2} + 8 x + 5}{{(5 x + 2)}^{2}}$

Step 5

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

$\frac{d y}{d x} = \frac{10 x^{2} + 8 x + 5}{{(5 x + 2)}^{2}}$