What is the derivative of this function y=cot^-1(sqrt(x-1))?

1 Answer
Aug 9, 2018

(dy)/(dx)=-1/(2xsqrt(x-1))

Explanation:

Here ,

y=cot^-1(sqrt(x-1))

Let ,

y=cot^-1u and u=sqrt(x-1)

:.(dy)/(du)=-1/(1+u^2) and (du)/(dx)=1/(2sqrt(x-1)

Using Chain Rule:

color(blue)((dy)/(dx)=(dy)/(du)(du)/(dx)

:.(dy)/(dx)=(-1)/(1+u^2)*1/(2sqrt(x-1))

Subst. u=sqrt(x-1)

:.(dy)/(dx)=-1/(1+(sqrt(x-1))^2) xx1/(2sqrt(x-1))

:.(dy)/(dx)=-1/(1+x-1)xx1/(2sqrt(x-1))

:.(dy)/(dx)=-1/(2xsqrt(x-1))