Find the differentiation of y=cos^-1(ax)?

1 Answer
Apr 27, 2018

y=cos^-1(ax)=>(dy)/(dx)=-1/sqrt(1-(ax)^2)d/(dx)(ax)y=cos1(ax)dydx=11(ax)2ddx(ax)
(dy)/(dx)=-1/sqrt(1-a^2x^2)xxa=(-a)/sqrt(1-a^2x^2)dydx=11a2x2×a=a1a2x2
Note: color(red)(d/(dX)(cos^-1X)=-1/sqrt(1-X^2)ddX(cos1X)=11X2

Explanation:

Here,

y=cos^-1(ax)y=cos1(ax)

Let, u=ax=>(du)/(dx)=au=axdudx=a

So, y=cos^-1u=>(dy)/(du)=-1/sqrt(1-u^2)So,y=cos1udydu=11u2

"Using "color(blue)"Chain Rule"Using Chain Rule,

color(blue)((dy)/(dx)=(dy)/(du)*(du)/(dx)dydx=dydududx

:.(dy)/(dx)=-1/sqrt(1-u^2)xxa=(-a)/sqrt(1-u^2),where, u=ax

=>(dy)/(dx)=(-a)/sqrt(1-(ax)^2)

=>(dy)/(dx)=(-a)/sqrt(1-a^2x^2)