Page 1 of 1

tangent to inverse function?

Posted: Wed Aug 03, 2011 2:24 am
by hadimotamedi
Dear All
For the function 'f' as :
f(x)=x - 1/x ; x >0
for which value of 'a' the line '2y-x=a' is tangent to the curve of f^(-1) (inverse function of f)?
Thank you

Re: tangent to inverse function?

Posted: Mon Aug 08, 2011 2:02 am
by hadimotamedi
Dear All
I figured out that the question can be solved as the following :
point A(α,β) on the function f(x) curve
point A^'(β,α) on the function f^(-1)(x)
So the slope of tangent to the f^(-1) curve is :
d/dx f^(-1)(β) = 1/d/dxf(α)
And the slope of normal line to the curve is as :
m.m^'= -1
Please comment me if you agree with me.

Re: tangent to inverse function?

Posted: Sun Aug 24, 2014 3:13 am
by DDswife
Seems about right to me