I need help with algebra 2

Set up an integral for the volume of the solid obtained by rotating the region bounded by the given curves about the specified l

Sloan [31]

Answer:

The integral of the volume is:

$V = 32\pi\int\limits^1_0 {\sqrt{(1 - y^2)} \, dy$

The result is: $V = 78.97731$

Step-by-step explanation:

Given

Curve: $x^2 + 4y^2 = 4$

About line $x = 2$ --- Missing information

Required

Set up an integral for the volume

$x^2 + 4y^2 = 4$

Make x^2 the subject

$x^2 = 4 - 4y^2$

Square both sides

$x = \sqrt{(4 - 4y^2)$

Factor out 4

$x = \sqrt{4(1 - y^2)$

Split

$x = \sqrt{4} * \sqrt{(1 - y^2)$

$x = \±2 * \sqrt{(1 - y^2)$

$x = \±2 \sqrt{(1 - y^2)$

Split

$x_1 = -2 \sqrt{(1 - y^2)}\ and\ x_2 = 2 \sqrt{(1 - y^2)}$

Rotate about x = 2 implies that:

$r = 2 - x$

So:

$r_1 = 2 - (-2 \sqrt{(1 - y^2)})$

$r_1 = 2 +2 \sqrt{(1 - y^2)}$

$r_2 = 2 - 2 \sqrt{(1 - y^2)}$

Using washer method along the y-axis i.e. integral from 0 to 1.

We have:

$V = 2\pi\int\limits^1_0 {(r_1^2 - r_2^2)} \, dy$

Substitute values for r1 and r2

$V = 2\pi\int\limits^1_0 {(( 2 +2 \sqrt{(1 - y^2)})^2 - ( 2 -2 \sqrt{(1 - y^2)})^2)} \, dy$

Evaluate the squares

$V = 2\pi\int\limits^1_0 {(4 +8 \sqrt{(1 - y^2)} + 4(1 - y^2)) - (4 -8 \sqrt{(1 - y^2)} + 4(1 - y^2))} \, dy$

Remove brackets and collect like terms

$V = 2\pi\int\limits^1_0 {4 - 4 + 8\sqrt{(1 - y^2)} +8 \sqrt{(1 - y^2)}+ 4(1 - y^2) - 4(1 - y^2)} \, dy$

$V = 2\pi\int\limits^1_0 { 16\sqrt{(1 - y^2)} \, dy$

Rewrite as:

$V = 16* 2\pi\int\limits^1_0 {\sqrt{(1 - y^2)} \, dy$

$V = 32\pi\int\limits^1_0 {\sqrt{(1 - y^2)} \, dy$

Using the calculator:

$\int\limits^1_0 {\sqrt{(1 - y^2)} \, dy = \frac{\pi}{4}$

So:

$V = 32\pi\int\limits^1_0 {\sqrt{(1 - y^2)} \, dy$

$V = 32\pi * \frac{\pi}{4}$

$V =\frac{32\pi^2}{4}$

$V =8\pi^2$

Take:

$\pi = 3.142$

$V = 8* 3.142^2$

$V = 78.97731$ --- approximated

3 0

3 years ago

A balloon has a circumference of 11 cm. Approximate the surface area of the balloon to the nearest tenth.

Shalnov [3]

Answer:

1520.5 cm²

Step-by-step explanation:

Surface area of a sphere =

A = 4πr²

= 4 x π x (11)²

= 1520.530844

= 1520.5 cm²

7 0

3 years ago

Use the clustering estimation technique to find the approximate total in the following question.

Stolb23 [73]

Answer:

2530

Step-by-step explanation:

First Round each number to the nearest 10s

503 into 500

472 into 470

499 into 500

539 into 540

522 into 520

then add the numbers we made

500+470+500+540+520=2530

the real answer is 2535 so its close

4 0

3 years ago

Read 2 more answers

A student collects 12 ladybugs for a science project. This is 9 fewer than the number of ladybugs the students collected yesterd

krok68 [10]

They collected 3 ladybugs yesterday

6 0

3 years ago

Read 2 more answers

Sunny earns \$12$12dollar sign, 12 per hour delivering cakes. She worked for xxx hours this week. Unfortunately, she was charged

dezoksy [38]

Answer:

12x - 15 dollars

Step-by-step explanation:

Sunny earns $12 per hour for delivering cakes.

She worked for x hours this week.

Unfortunately, she was charged $15 for a late delivery on Tuesday

She was supposed to earn $12 × x = $12x this week

But she was charged $15 for late delivery on Tuesday

So her net earning this week is; $12x - $15

7 0

3 years ago