The formula for the volume of a sphere is y = 4/3 pi r^3 .
a. Solve the formula for r and write using positive rational exponents.
b. Find the radius, to the nearest hundredth, of a sphere with a volume of 15 in.3

Question

The formula for the volume of a sphere is y = 4/3 pi r^3 . 
a. Solve the formula for r and write using positive rational exponents. 
b. Find the radius, to the nearest hundredth, of a sphere with a volume of 15 in.3

tyteen4a03 · Answer

a. The idea is to make r the subject (r = something). The ^3 part in r needs to be gotten rid of too.
b. Finish a, and plug in the numbers.

anonymous · Answer

can you help me with getting r by itself, im having trouble

anonymous · Answer

@tyteen4a03

tyteen4a03 · Answer

y = 4/3 pi r^3

To start off, move everything that is not r to the LHS. This means we'll be dividing both sides by 4pi/3:

3y / 4pi = r^3.

We know the inverse of r ^3 is r ^ 1/3 (i.e cube root), so cube root both sides and get the answer.

anonymous · Answer

I understood everything up to that point just not how to cube root 3y/pi

tyteen4a03 · Answer

Basically wrap a cube root around it. $\sqrt[3]{Stuff goes here}$

anonymous · Answer

so I dont think this is right but I got y/1.5 = r

tyteen4a03 · Answer

You should leave the surd roots intact. BTW, your answer is incorrect.

anonymous · Answer

oh okay. and you mean dont do anything to the left side?

tyteen4a03 · Answer

@forty-two Basically if you see $\sqrt[3]{xbr}$, leave this term as-is.