SOLUTION: A cylinder has a volume of 32 in^3. If the height of the cylinder is 5 inches more than radius, find the radius of the cylinder.

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Question 1025412: A cylinder has a volume of 32 in^3. If the height of the cylinder is 5 inches more than radius, find the radius of the cylinder.
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
r for radius, h for height,
h=r%2B5

h%2Api%2Ar%5E2=32


%28r%2B5%29pi%2Ar%5E2=32
r%5E2%28r%2B5%29pi=32
r%5E3%2B5r%5E2=32%2Fpi
r%5E3%2B5r%5E2-32%2Fpi=0

Use any method you know for finding roots of that equation. This is not something that Rational Roots Theorem will help with. Maybe try a graphing tool.



graph%28400%2C400%2C-3%2C7%2C-3%2C7%2Cx%5E3%2B5x%5E2-32%2Fpi%29

graph%28400%2C400%2C-3%2C12%2C-3%2C12%2Cx%5E3%2B5x%5E2-32%2Fpi%29

Closer look:
graph%28400%2C400%2C0%2C3%2C0%2C2%2Cx%5E3%2B5x%5E2-32%2Fpi%29