9709/Oct Nov/13/2016/Q8

(i) Express 4x² + 12x + 10 in the form (ax + b)² + c, where a, b and c are constants.

(ii) Functions f and g are both defined for x > 0. It is given that f(x) = x² + 1 and fg(x) = 4x² + 12x + 10. Find g(x).

(iii) Find (fg)⁻¹ (x) and give the domain of (fg)⁻¹.

Solution:

Reference: PYQ - Oct/Nov 2016 Paper 13 Q8