Calculus Examples

$y = 3 \sqrt{2 x^{2} - x - 4}$

Step 1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{2 x^{2} - x - 4}$ as ${(2 x^{2} - x - 4)}^{\frac{1}{2}}$ .

$y = 3 {(2 x^{2} - x - 4)}^{\frac{1}{2}}$

Step 2

Differentiate both sides of the equation.

$\frac{d}{d x} (y) = \frac{d}{d x} (3 {(2 x^{2} - x - 4)}^{\frac{1}{2}})$

Step 3

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

$y'$

Step 4

Differentiate the right side of the equation.

Tap for more steps...

Step 4.1

Since $3$ is constant with respect to $x$ , the derivative of $3 {(2 x^{2} - x - 4)}^{\frac{1}{2}}$ with respect to $x$ is $3 \frac{d}{d x} [{(2 x^{2} - x - 4)}^{\frac{1}{2}}]$ .

$3 \frac{d}{d x} [{(2 x^{2} - x - 4)}^{\frac{1}{2}}]$

Step 4.2

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = x^{\frac{1}{2}}$ and $g (x) = 2 x^{2} - x - 4$ .

Tap for more steps...

Step 4.2.1

To apply the Chain Rule, set $u$ as $2 x^{2} - x - 4$ .

$3 (\frac{d}{d u} [u^{\frac{1}{2}}] \frac{d}{d x} [2 x^{2} - x - 4])$

Step 4.2.2

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

$3 (\frac{1}{2} u^{\frac{1}{2} - 1} \frac{d}{d x} [2 x^{2} - x - 4])$

Step 4.2.3

Replace all occurrences of $u$ with $2 x^{2} - x - 4$ .

$3 (\frac{1}{2} {(2 x^{2} - x - 4)}^{\frac{1}{2} - 1} \frac{d}{d x} [2 x^{2} - x - 4])$

Step 4.3

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$3 (\frac{1}{2} {(2 x^{2} - x - 4)}^{\frac{1}{2} - 1 \cdot \frac{2}{2}} \frac{d}{d x} [2 x^{2} - x - 4])$

Step 4.4

Combine $- 1$ and $\frac{2}{2}$ .

$3 (\frac{1}{2} {(2 x^{2} - x - 4)}^{\frac{1}{2} + \frac{- 1 \cdot 2}{2}} \frac{d}{d x} [2 x^{2} - x - 4])$

Step 4.5

Combine the numerators over the common denominator.

$3 (\frac{1}{2} {(2 x^{2} - x - 4)}^{\frac{1 - 1 \cdot 2}{2}} \frac{d}{d x} [2 x^{2} - x - 4])$

Step 4.6

Simplify the numerator.

Tap for more steps...

Step 4.6.1

Multiply $- 1$ by $2$ .

$3 (\frac{1}{2} {(2 x^{2} - x - 4)}^{\frac{1 - 2}{2}} \frac{d}{d x} [2 x^{2} - x - 4])$

Step 4.6.2

Subtract $2$ from $1$ .

$3 (\frac{1}{2} {(2 x^{2} - x - 4)}^{\frac{- 1}{2}} \frac{d}{d x} [2 x^{2} - x - 4])$

Step 4.7

Combine fractions.

Tap for more steps...

Step 4.7.1

Move the negative in front of the fraction.

$3 (\frac{1}{2} {(2 x^{2} - x - 4)}^{- \frac{1}{2}} \frac{d}{d x} [2 x^{2} - x - 4])$

Step 4.7.2

Combine $\frac{1}{2}$ and ${(2 x^{2} - x - 4)}^{- \frac{1}{2}}$ .

$3 (\frac{{(2 x^{2} - x - 4)}^{- \frac{1}{2}}}{2} \frac{d}{d x} [2 x^{2} - x - 4])$

Step 4.7.3

Move ${(2 x^{2} - x - 4)}^{- \frac{1}{2}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$3 (\frac{1}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}} \frac{d}{d x} [2 x^{2} - x - 4])$

Step 4.7.4

Combine $\frac{1}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}}$ and $3$ .

$\frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}} \frac{d}{d x} [2 x^{2} - x - 4]$

Step 4.8

By the Sum Rule, the derivative of $2 x^{2} - x - 4$ with respect to $x$ is $\frac{d}{d x} [2 x^{2}] + \frac{d}{d x} [- x] + \frac{d}{d x} [- 4]$ .

$\frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}} (\frac{d}{d x} [2 x^{2}] + \frac{d}{d x} [- x] + \frac{d}{d x} [- 4])$

Step 4.9

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

$\frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}} (2 \frac{d}{d x} [x^{2}] + \frac{d}{d x} [- x] + \frac{d}{d x} [- 4])$

Step 4.10

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

$\frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}} (2 (2 x) + \frac{d}{d x} [- x] + \frac{d}{d x} [- 4])$

Step 4.11

Multiply $2$ by $2$ .

$\frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}} (4 x + \frac{d}{d x} [- x] + \frac{d}{d x} [- 4])$

Step 4.12

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

$\frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}} (4 x - \frac{d}{d x} [x] + \frac{d}{d x} [- 4])$

Step 4.13

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

$\frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}} (4 x - 1 \cdot 1 + \frac{d}{d x} [- 4])$

Step 4.14

Multiply $- 1$ by $1$ .

$\frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}} (4 x - 1 + \frac{d}{d x} [- 4])$

Step 4.15

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

$\frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}} (4 x - 1 + 0)$

Step 4.16

Add $4 x - 1$ and $0$ .

$\frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}} (4 x - 1)$

Step 4.17

Simplify.

Tap for more steps...

Step 4.17.1

Reorder the factors of $\frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}} (4 x - 1)$ .

$(4 x - 1) \frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}}$

Step 4.17.2

Multiply $4 x - 1$ by $\frac{3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}}$ .

$\frac{(4 x - 1) \cdot 3}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}}$

Step 4.17.3

Move $3$ to the left of $4 x - 1$ .

$\frac{3 (4 x - 1)}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}}$

Step 5

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

$y' = \frac{3 (4 x - 1)}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}}$

Step 6

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

$\frac{d y}{d x} = \frac{3 (4 x - 1)}{2 {(2 x^{2} - x - 4)}^{\frac{1}{2}}}$