Question

If f : R → R, f(x) = 2x – 3; g : R → R, g(x) = x3 + 5, then the value of (fog)-1 (x):

Answer 1

Answer is (d)

Given,

f : R → R, f(x) = 2x – 3

g : R → R, g(x)= x3 + 5

∴ (fog)(x) = f(g(x)]

= f(x3 +5)

= 2(x3 + 5) – 3 = 2x3 + 10 – 3

= 2x3 + 7

Let y = (fog)(x) = 2x3 + 7

∴ (fog)-1(y) = x