dse question doubt

Posted by bhavya jain on Mar 07, 2014; 6:53am
URL: http://discussion-forum.276.s1.nabble.com/dse-question-doubt-tp7585098.html

someone plz tell me how to solve this question;
Q) Consider the function defined by f(x)=x^6+5x^4+2, for all x>=0. The derivative of its inverse function evaluated at f(x)=8, is
a)1/7
b)1/15
c)1/26
d)1/30