Let f : Q → Q : f(x) = (2x + 3). Then, f^- 1(y) = ?

Question

Mark (√) against the correct answer in the following: 

Let f : Q → Q : f(x) = (2x + 3). Then, f^-1(y) = ?

A. (2y - 3)

B. \(\frac{1}{(2y-3)}\)

C. \(\frac{1}{2}(y-3)\)

D. none of these

Answer 1

Correct Answer is (D) none of these

f(x) = 2x + 3

⇒y = 2x + 3

x ⟺ y

⇒x = 2y + 3

⇒x - 3 = 2y

\(\Rightarrow \frac{x-3}{2}=y\)

x ⟺ y

\(\Rightarrow \frac{y-3}{2}=x\)