Calculus Examples

$y = x^{2} \log_{2} (5 - 4 x)$

Step 1

Differentiate both sides of the equation.

$\frac{d}{d x} (y) = \frac{d}{d x} (x^{2} \log_{2} (5 - 4 x))$

Step 2

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

$y'$

Step 3

Differentiate the right side of the equation.

Tap for more steps...

Step 3.1

Differentiate using the Product Rule which states that $\frac{d}{d x} [f (x) g (x)]$ is $f (x) \frac{d}{d x} [g (x)] + g (x) \frac{d}{d x} [f (x)]$ where $f (x) = x^{2}$ and $g (x) = \log_{2} (5 - 4 x)$ .

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

Step 3.2

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = \log_{2} (x)$ and $g (x) = 5 - 4 x$ .

Tap for more steps...

Step 3.2.1

To apply the Chain Rule, set $u$ as $5 - 4 x$ .

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

Step 3.2.2

The derivative of $\log_{2} (u)$ with respect to $u$ is $\frac{1}{u \ln (2)}$ .

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

Step 3.2.3

Replace all occurrences of $u$ with $5 - 4 x$ .

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

Step 3.3

Differentiate.

Tap for more steps...

Step 3.3.1

Combine $\frac{1}{(5 - 4 x) \ln (2)}$ and $x^{2}$ .

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

Step 3.3.2

By the Sum Rule, the derivative of $5 - 4 x$ with respect to $x$ is $\frac{d}{d x} [5] + \frac{d}{d x} [- 4 x]$ .

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

Step 3.3.3

Since $5$ is constant with respect to $x$ , the derivative of $5$ with respect to $x$ is $0$ .

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

Step 3.3.4

Add $0$ and $\frac{d}{d x} [- 4 x]$ .

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

Step 3.3.5

Since $- 4$ is constant with respect to $x$ , the derivative of $- 4 x$ with respect to $x$ is $- 4 \frac{d}{d x} [x]$ .

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

Step 3.3.6

Combine fractions.

Tap for more steps...

Step 3.3.6.1

Combine $- 4$ and $\frac{x^{2}}{(5 - 4 x) \ln (2)}$ .

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

Step 3.3.6.2

Move the negative in front of the fraction.

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

Step 3.3.7

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

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

Step 3.3.8

Multiply $- 1$ by $1$ .

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

Step 3.3.9

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

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

Step 3.3.10

Move $\log_{2} (- 4 x + 5)$ .

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

Step 3.4

To write $2 x \log_{2} (- 4 x + 5)$ as a fraction with a common denominator, multiply by $\frac{(- 4 x + 5) \ln (2)}{(- 4 x + 5) \ln (2)}$ .

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

Step 3.5

Combine $2 x \log_{2} (- 4 x + 5)$ and $\frac{(- 4 x + 5) \ln (2)}{(- 4 x + 5) \ln (2)}$ .

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

Step 3.6

Combine the numerators over the common denominator.

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

Step 3.7

Simplify.

Tap for more steps...

Step 3.7.1

Apply the distributive property.

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

Step 3.7.2

Apply the distributive property.

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

Step 3.7.3

Simplify the numerator.

Tap for more steps...

Step 3.7.3.1

Simplify each term.

Tap for more steps...

Step 3.7.3.1.1

Simplify $2 \log_{2} (- 4 x + 5)$ by moving $2$ inside the logarithm.

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

Step 3.7.3.1.2

Simplify each term.

Tap for more steps...

Step 3.7.3.1.2.1

Simplify $- 4 \ln (2)$ by moving $4$ inside the logarithm.

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

Step 3.7.3.1.2.2

Raise $2$ to the power of $4$ .

$\frac{- 4 x^{2} + x \log_{2} ({(- 4 x + 5)}^{2}) (x (- \ln (16)) + 5 \ln (2))}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.3.1.2.3

Simplify $5 \ln (2)$ by moving $5$ inside the logarithm.

$\frac{- 4 x^{2} + x \log_{2} ({(- 4 x + 5)}^{2}) (x (- \ln (16)) + \ln (2^{5}))}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.3.1.2.4

Raise $2$ to the power of $5$ .

$\frac{- 4 x^{2} + x \log_{2} ({(- 4 x + 5)}^{2}) (x (- \ln (16)) + \ln (32))}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.3.1.3

Apply the distributive property.

$\frac{- 4 x^{2} + x \log_{2} ({(- 4 x + 5)}^{2}) (x (- \ln (16))) + x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32)}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.3.1.4

Rewrite using the commutative property of multiplication.

$\frac{- 4 x^{2} - \ln (16) x \log_{2} ({(- 4 x + 5)}^{2}) x + x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32)}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.3.1.5

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

Tap for more steps...

Step 3.7.3.1.5.1

Move $x$ .

$\frac{- 4 x^{2} - \ln (16) (x \cdot x) \log_{2} ({(- 4 x + 5)}^{2}) + x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32)}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.3.1.5.2

Multiply $x$ by $x$ .

$\frac{- 4 x^{2} - \ln (16) x^{2} \log_{2} ({(- 4 x + 5)}^{2}) + x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32)}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.3.2

Reorder factors in $- 4 x^{2} - \ln (16) x^{2} \log_{2} ({(- 4 x + 5)}^{2}) + x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32)$ .

$\frac{- 4 x^{2} - x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) + x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32)}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.4

Factor $- 1$ out of $- 4 x^{2}$ .

$\frac{- (4 x^{2}) - x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) + x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32)}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.5

Factor $- 1$ out of $- x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2})$ .

$\frac{- (4 x^{2}) - (x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2})) + x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32)}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.6

Factor $- 1$ out of $- (4 x^{2}) - (x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}))$ .

$\frac{- (4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2})) + x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32)}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.7

Factor $- 1$ out of $x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32)$ .

$\frac{- (4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2})) - (- x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32))}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.8

Factor $- 1$ out of $- (4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2})) - (- x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32))$ .

$\frac{- (4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32))}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.9

Rewrite $- (4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32))$ as $- 1 (4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32))$ .

$\frac{- 1 (4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32))}{- 4 x \ln (2) + 5 \ln (2)}$

Step 3.7.10

Factor $- 1$ out of $- 4 x \ln (2)$ .

$\frac{- 1 (4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32))}{- (4 x \ln (2)) + 5 \ln (2)}$

Step 3.7.11

Factor $- 1$ out of $5 \ln (2)$ .

$\frac{- 1 (4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32))}{- (4 x \ln (2)) - (- 5 \ln (2))}$

Step 3.7.12

Factor $- 1$ out of $- (4 x \ln (2)) - (- 5 \ln (2))$ .

$\frac{- 1 (4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32))}{- (4 x \ln (2) - 5 \ln (2))}$

Step 3.7.13

Rewrite $- (4 x \ln (2) - 5 \ln (2))$ as $- 1 (4 x \ln (2) - 5 \ln (2))$ .

$\frac{- 1 (4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32))}{- 1 (4 x \ln (2) - 5 \ln (2))}$

Step 3.7.14

Cancel the common factor.

$\frac{- 1 (4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32))}{- 1 (4 x \ln (2) - 5 \ln (2))}$

Step 3.7.15

Rewrite the expression.

$\frac{4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \log_{2} ({(- 4 x + 5)}^{2}) \ln (32)}{4 x \ln (2) - 5 \ln (2)}$

Step 3.7.16

Reorder terms.

$\frac{4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \ln (32) \log_{2} ({(- 4 x + 5)}^{2})}{4 x \ln (2) - 5 \ln (2)}$

Step 4

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

$y' = \frac{4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \ln (32) \log_{2} ({(- 4 x + 5)}^{2})}{4 x \ln (2) - 5 \ln (2)}$

Step 5

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

$\frac{d y}{d x} = \frac{4 x^{2} + x^{2} \ln (16) \log_{2} ({(- 4 x + 5)}^{2}) - x \ln (32) \log_{2} ({(- 4 x + 5)}^{2})}{4 x \ln (2) - 5 \ln (2)}$