A cylinder with radius r and height 2r + 4 contains a cube with edge r *squared sign* 2 as shown. What fraction of rhe cylinder's volume is taken up by the cube? Write you answer in simplified form. I don't understand...help? :/

Question

anonymous · Answer

attachment

saifoo.khan · Answer

First of all find the area of the cylinder.

saifoo.khan · Answer

Do you know it's formula?

anonymous · Answer

nope :/ i've been behind in school and now i have to rush and finish everything and i don't understand

saifoo.khan · Answer

The formula for the volume of cylinder is,
$$base area \times height$$$$\pi r^2 \times height$$

anonymous · Answer

ohh. so it's going to be 2r + 4 multiplied by r *squared* 2?

saifoo.khan · Answer

Yes!

anonymous · Answer

the variables are confusing me

saifoo.khan · Answer

$$\large \pi r^2  (2r + 4) $$$$\large   (2\pi r^3 + 4\pi r^2) $$

saifoo.khan · Answer

That's the volume of cylinder..
Do you get till here?

anonymous · Answer

yess

saifoo.khan · Answer

Now the formula for cube = L^3
$$\Large (r^2)^3 \to r^6$$

anonymous · Answer

so multiply (2pir^3 + 4pir^2) by r^6?

saifoo.khan · Answer

No, now it says "what fraction"/

so i think we have to divide them.

anonymous · Answer

ohh

anonymous · Answer

can you help me with that too?

saifoo.khan · Answer

Take r common from the volume of cylinder.

anonymous · Answer

r common?

saifoo.khan · Answer

$$\Large r^2(2 \pi r + 4 \pi )$$

anonymous · Answer

is that the answer or is there more simplifying and whatnot?

anonymous · Answer

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