What is f^-1(−2 given that f(x) = (x +1)/2

Question

Given that f(x) = (x +1)/2, find f^-1(−2)

Answer 1

y= (x+1)/2

switch x and y, then solve for the new y

x=(y+1)/2 = y/2 + 1/2

2x = y+ 1

y =2x -1

f^-1(x) = 2x -1

f^-1(-2) = 2(-2) -1 = -4-1 = -5

f^-1(-2) =-5