Inverse function problem

May 2019
11
0
moscow
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? Thanks1.png2.png
 
Last edited:
Jun 2013
1,112
590
Lebanon
it should be

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

now replace $A=200$
 
Last edited:
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Aug 2007
3,171
860
USA
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.
 
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