SOLUTION: A cone has a volume of 125π cubic units. It has a radius of 2x-5 units and a height of 3x units. What is the radius of the cone?

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: A cone has a volume of 125π cubic units. It has a radius of 2x-5 units and a height of 3x units. What is the radius of the cone?      Log On


   

Question 1171346: A cone has a volume of 125π cubic units. It has a radius of 2x-5 units and a height of 3x units. What is the radius of the cone?
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


V+=+%281%2F3%29%28pi%29%28r%5E2%29%28h%29

125%28pi%29+=+%281%2F3%29%28pi%29%28%282x-5%29%5E2%29%283x%29

125+=+%28%282x-5%29%5E2%29%28x%29

That's going to give you a cubic equation that you will need to solve....

So let's guess that the answer is a "nice" number.

125 = 5*5*5 gives us a clue; and a bit of easy mental arithmetic shows the solution is x=5.

ANSWER: The radius is 2x-5 = 5 units.