If f(x) = (x^2 – 1) and g(x) = (2x + 3) then (g o f) (x) = ?

Question

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

If f(x) = (x² – 1) and g(x) = (2x + 3) then (g o f) (x) = ? 

A. (2x² + 3) 

B. (3x² + 2) 

C. (2x² + 1) 

D. None of these

Answer 1

Correct Answer is (C) (2x² + 1) 

f(x) = (x² – 1)

g(x) = (2x + 3)

∴(g o f) (x) = g(f(x))

\(\Rightarrow g(f(x))=2f(x)+3\)

\(\Rightarrow g(f(x))\)\(=2((x^2-1))+3\)\(=2x^2-2+3\)\(=2x^2+1\)