Question 164428
let f(x)=y then x=f^-1(y)
given f(x)= -sqrt(1-x)
that is y = -sqrt(1-x)
squaring on both sides we get, y^2 = 1-x
x = 1-y^2 and x = f^-1(y)
so f^-1(y) = 1-y^2
hence f^-1(x) = 1-x^2