Calculus Examples

$y = x^{2}$ , $y = 4 x$

Step 1

To find the volume of the solid, first define the area of each slice then integrate across the range. The area of each slice is the area of a circle with radius $f (x)$ and $A = π r^{2}$ .

$V = π \int_{0}^{4} {(f (x))}^{2} - {(g (x))}^{2} d x$ where $f (x) = 4 x$ and $g (x) = x^{2}$

Step 2

Simplify each term.

Tap for more steps...

Step 2.1

Apply the product rule to $4 x$ .

$V = 4^{2} x^{2} - {(x^{2})}^{2}$

Step 2.2

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

$V = 16 x^{2} - {(x^{2})}^{2}$

Step 2.3

Multiply the exponents in ${(x^{2})}^{2}$ .

Tap for more steps...

Step 2.3.1

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$V = 16 x^{2} - x^{2 \cdot 2}$

Step 2.3.2

Multiply $2$ by $2$ .

$V = 16 x^{2} - x^{4}$

Step 3

Split the single integral into multiple integrals.

$V = π (\int_{0}^{4} 16 x^{2} d x + \int_{0}^{4} - x^{4} d x)$

Step 4

Since $16$ is constant with respect to $x$ , move $16$ out of the integral.

$V = π (16 \int_{0}^{4} x^{2} d x + \int_{0}^{4} - x^{4} d x)$

Step 5

By the Power Rule, the integral of $x^{2}$ with respect to $x$ is $\frac{1}{3} x^{3}$ .

$V = π (16 (\frac{1}{3} x^{3}]_{0}^{4}) + \int_{0}^{4} - x^{4} d x)$

Step 6

Combine $\frac{1}{3}$ and $x^{3}$ .

$V = π (16 (\frac{x^{3}}{3}]_{0}^{4}) + \int_{0}^{4} - x^{4} d x)$

Step 7

Since $- 1$ is constant with respect to $x$ , move $- 1$ out of the integral.

$V = π (16 (\frac{x^{3}}{3}]_{0}^{4}) - \int_{0}^{4} x^{4} d x)$

Step 8

By the Power Rule, the integral of $x^{4}$ with respect to $x$ is $\frac{1}{5} x^{5}$ .

$V = π (16 (\frac{x^{3}}{3}]_{0}^{4}) - (\frac{1}{5} x^{5}]_{0}^{4}))$

Step 9

Simplify the answer.

Tap for more steps...

Step 9.1

Combine $\frac{1}{5}$ and $x^{5}$ .

$V = π (16 (\frac{x^{3}}{3}]_{0}^{4}) - (\frac{x^{5}}{5}]_{0}^{4}))$

Step 9.2

Substitute and simplify.

Tap for more steps...

Step 9.2.1

Evaluate $\frac{x^{3}}{3}$ at $4$ and at $0$ .

$V = π (16 ((\frac{4^{3}}{3}) - \frac{0^{3}}{3}) - (\frac{x^{5}}{5}]_{0}^{4}))$

Step 9.2.2

Evaluate $\frac{x^{5}}{5}$ at $4$ and at $0$ .

$V = π (16 (\frac{4^{3}}{3} - \frac{0^{3}}{3}) - (\frac{4^{5}}{5} - \frac{0^{5}}{5}))$

Step 9.2.3

Simplify.

Tap for more steps...

Step 9.2.3.1

Raise $4$ to the power of $3$ .

$V = π (16 (\frac{64}{3} - \frac{0^{3}}{3}) - (\frac{4^{5}}{5} - \frac{0^{5}}{5}))$

Step 9.2.3.2

Raising $0$ to any positive power yields $0$ .

$V = π (16 (\frac{64}{3} - \frac{0}{3}) - (\frac{4^{5}}{5} - \frac{0^{5}}{5}))$

Step 9.2.3.3

Cancel the common factor of $0$ and $3$ .

Tap for more steps...

Step 9.2.3.3.1

Factor $3$ out of $0$ .

$V = π (16 (\frac{64}{3} - \frac{3 (0)}{3}) - (\frac{4^{5}}{5} - \frac{0^{5}}{5}))$

Step 9.2.3.3.2

Cancel the common factors.

Tap for more steps...

Step 9.2.3.3.2.1

Factor $3$ out of $3$ .

$V = π (16 (\frac{64}{3} - \frac{3 \cdot 0}{3 \cdot 1}) - (\frac{4^{5}}{5} - \frac{0^{5}}{5}))$

Step 9.2.3.3.2.2

Cancel the common factor.

$V = π (16 (\frac{64}{3} - \frac{3 \cdot 0}{3 \cdot 1}) - (\frac{4^{5}}{5} - \frac{0^{5}}{5}))$

Step 9.2.3.3.2.3

Rewrite the expression.

$V = π (16 (\frac{64}{3} - \frac{0}{1}) - (\frac{4^{5}}{5} - \frac{0^{5}}{5}))$

Step 9.2.3.3.2.4

Divide $0$ by $1$ .

$V = π (16 (\frac{64}{3} - 0) - (\frac{4^{5}}{5} - \frac{0^{5}}{5}))$

Step 9.2.3.4

Multiply $- 1$ by $0$ .

$V = π (16 (\frac{64}{3} + 0) - (\frac{4^{5}}{5} - \frac{0^{5}}{5}))$

Step 9.2.3.5

Add $\frac{64}{3}$ and $0$ .

$V = π (16 (\frac{64}{3}) - (\frac{4^{5}}{5} - \frac{0^{5}}{5}))$

Step 9.2.3.6

Combine $16$ and $\frac{64}{3}$ .

$V = π (\frac{16 \cdot 64}{3} - (\frac{4^{5}}{5} - \frac{0^{5}}{5}))$

Step 9.2.3.7

Multiply $16$ by $64$ .

$V = π (\frac{1024}{3} - (\frac{4^{5}}{5} - \frac{0^{5}}{5}))$

Step 9.2.3.8

Raise $4$ to the power of $5$ .

$V = π (\frac{1024}{3} - (\frac{1024}{5} - \frac{0^{5}}{5}))$

Step 9.2.3.9

Raising $0$ to any positive power yields $0$ .

$V = π (\frac{1024}{3} - (\frac{1024}{5} - \frac{0}{5}))$

Step 9.2.3.10

Cancel the common factor of $0$ and $5$ .

Tap for more steps...

Step 9.2.3.10.1

Factor $5$ out of $0$ .

$V = π (\frac{1024}{3} - (\frac{1024}{5} - \frac{5 (0)}{5}))$

Step 9.2.3.10.2

Cancel the common factors.

Tap for more steps...

Step 9.2.3.10.2.1

Factor $5$ out of $5$ .

$V = π (\frac{1024}{3} - (\frac{1024}{5} - \frac{5 \cdot 0}{5 \cdot 1}))$

Step 9.2.3.10.2.2

Cancel the common factor.

$V = π (\frac{1024}{3} - (\frac{1024}{5} - \frac{5 \cdot 0}{5 \cdot 1}))$

Step 9.2.3.10.2.3

Rewrite the expression.

$V = π (\frac{1024}{3} - (\frac{1024}{5} - \frac{0}{1}))$

Step 9.2.3.10.2.4

Divide $0$ by $1$ .

$V = π (\frac{1024}{3} - (\frac{1024}{5} - 0))$

Step 9.2.3.11

Multiply $- 1$ by $0$ .

$V = π (\frac{1024}{3} - (\frac{1024}{5} + 0))$

Step 9.2.3.12

Add $\frac{1024}{5}$ and $0$ .

$V = π (\frac{1024}{3} - \frac{1024}{5})$

Step 9.2.3.13

To write $\frac{1024}{3}$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$V = π (\frac{1024}{3} \cdot \frac{5}{5} - \frac{1024}{5})$

Step 9.2.3.14

To write $- \frac{1024}{5}$ as a fraction with a common denominator, multiply by $\frac{3}{3}$ .

$V = π (\frac{1024}{3} \cdot \frac{5}{5} - \frac{1024}{5} \cdot \frac{3}{3})$

Step 9.2.3.15

Write each expression with a common denominator of $15$ , by multiplying each by an appropriate factor of $1$ .

Tap for more steps...

Step 9.2.3.15.1

Multiply $\frac{1024}{3}$ by $\frac{5}{5}$ .

$V = π (\frac{1024 \cdot 5}{3 \cdot 5} - \frac{1024}{5} \cdot \frac{3}{3})$

Step 9.2.3.15.2

Multiply $3$ by $5$ .

$V = π (\frac{1024 \cdot 5}{15} - \frac{1024}{5} \cdot \frac{3}{3})$

Step 9.2.3.15.3

Multiply $\frac{1024}{5}$ by $\frac{3}{3}$ .

$V = π (\frac{1024 \cdot 5}{15} - \frac{1024 \cdot 3}{5 \cdot 3})$

Step 9.2.3.15.4

Multiply $5$ by $3$ .

$V = π (\frac{1024 \cdot 5}{15} - \frac{1024 \cdot 3}{15})$

Step 9.2.3.16

Combine the numerators over the common denominator.

$V = π (\frac{1024 \cdot 5 - 1024 \cdot 3}{15})$

Step 9.2.3.17

Simplify the numerator.

Tap for more steps...

Step 9.2.3.17.1

Multiply $1024$ by $5$ .

$V = π (\frac{5120 - 1024 \cdot 3}{15})$

Step 9.2.3.17.2

Multiply $- 1024$ by $3$ .

$V = π (\frac{5120 - 3072}{15})$

Step 9.2.3.17.3

Subtract $3072$ from $5120$ .

$V = π (\frac{2048}{15})$

Step 9.2.3.18

Combine $π$ and $\frac{2048}{15}$ .

$V = \frac{π \cdot 2048}{15}$

Step 9.2.3.19

Move $2048$ to the left of $π$ .

$V = \frac{2048 π}{15}$

Step 10

The result can be shown in multiple forms.

Exact Form:

$V = \frac{2048 π}{15}$

Decimal Form:

$V = 428.93211697 \dots$

Step 11