Mathematics 9709 · AS & A Level · Functions

Functions — practice question

(i)[3]

Write $4x^2 + 12x + 10$ in the form $(ax + b)^2 + c$, with $a$, $b$ and $c$ as constants.

(ii)[1]

Both functions $f$ and $g$ are defined for $x > 0$. You are told that $f(x) = x^2 + 1$ and $fg(x) = 4x^2 + 12x + 10$. Determine $g(x)$.

(iii)[4]

Find $(fg)^{-1}(x)$ and state the domain of $(fg)^{-1}$.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: The correct form is $(2x+3)^2+1$.

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