Question

Lost in step 3:

2. Apply the formula of a right circular cylinder (V = r2h) to find the volume of the object.
3. Rewrite the formula using the variable x for the radius. Substitute the value of the volume found in step 2 for V and express the height of the object in terms of x plus or minus a constant. For example, if the height measurement is 4 inches longer than the radius, then the expression for the height will be (x + 4).

Diameter: 3in
Height: 4.5in
Volume: ≈31.8in

Answer 1

I think what it's saying is to let height be the radius (x) plus some value. Since your height is 4.5, and your diameter is 3, the radius is 1.5, so height = x+3. Also, V~31.8, so you would rewrite your equation as

V=x2(x+3)

Answer 2

ooops thinking SA

Answer 3

v=pi r^2 h

Answer 4

did you forget pi ?

Answer 5

Yes, pi should be there. :)

Answer 6

I'm a little confused by your original formula though. I though that \[V=\pi r^2 h\]Like mathg8 said.

Answer 7

Sorry, copy and pasted. Didn't realize that the pi symbol didn't transfer.

Answer 8

So then, using what I said earlier, \[V=\pi x^2 (x+3)\]

Answer 9

Now I:
Simplify the equation and write it in standard form. If the equation contains decimals, multiply each term by a constant that will make all coefficients integers.

Example: 0 = x3 + 2.75x2 – 6.25
If this equation is multiplied by 4, the decimals will become integers.
4(0 = x3 + 2.75x2 – 6.25)
0 = 4x3 + 11x2 – 25

Answer 10

Since \(V \sim 31.8\) you have \(31.8=\pi x^3+\pi 3x^2\). Here, \(31.8\) is the only decimal, so multiply by \(5\) to get rid of the decimal.

Answer 11

159=5pix^2+5pi3x^2
?

Answer 12

So you get \(0 \sim 5\pi x^3 + 15\pi x^2 -159\).

Now, the only problem I'm seeing, is that \(\pi\) isn't an integer, but there's no way to get rid of it. However, if you kept the original value of \(V\) in terms of \(\pi\), we could get rid of pi.

Answer 13

So, assuming that, we can use the original diameter and height to find that \[V=10.125 \pi = \pi x^3 +3 \pi x^2\]This is much better since we can now divide by \(\pi\) and multiply by \(8\) since \(0.125 = {1/8}\). Finally, that means that \[0=8x^3+24x^2-81\]

Answer 14

Thank you! I'm taking this class online, and have e-mailed my teacher asking for help multiple times. They don't seem as though they are willing to help, as they have never responded. Lol. :(

Answer 15

You're very welcome.

Answer 16

Which class is this?

Answer 17

Algebra II

Answer 18

I've always found algebra interesting.

Answer 19

Math is not a skill of mine, so I would have to disagree! Thank you again. :)

Answer 20

You're welcome. Feel free to ask any more questions.