Question

If f(x) =  3x - 5 , then f⁻¹ (x)

(A) Is given by1 3/( x − 5)

(B) Is given by(x + 5)/3

(C) Does not exist because f is not one-to-one

(D) Does not exist because f is not onto

Answer 1

Correct option  (B) Is given by (x + 5)/3

Explanation :

Let us consider

f (x) = y⇒ x = f^-1(y)

 Hence, 

 Therefore,

f^-1(x) = x + 5/3

Also f is one-to-one and onto and hence f −1 exists and is given by

f^-1(x) = x + 5/3