1. ## Inverse function problem

Hello
I have a folllowing question
Function A(r)=2*pi*r2+6*pi*r. I has a an inverse function r(A)=(-6*pi+-sqrt(4*pi(9*pi+2r))/4*pi
Calculate at what radius does the area of the cylinder equal 200. do i just make the function r(A)=200? Thanks

2. ## Re: Inverse function problem

it should be

$\displaystyle r=\frac{-6 \pi + \sqrt{4\pi (9 \pi +2A)}}{4 \pi }$

now replace $A=200$

3. ## Re: Inverse function problem

Originally Posted by dbag
I has a an inverse function r(A)=(-6*pi+-sqrt(4*pi(9*pi+2r))/4*pi
This is a very bad mistake. Understanding what a function is and isn't is SO fundamental. Please review the definition.