Mathematics 9709 · AS & A Level · Functions

Functions — practice question

For $x \in \mathbb{R}$, the functions $f$ and $g$ are given by $f: x \mapsto 4x - 2x^2$, $g: x \mapsto 5x + 3$.
(i)[2]

Find the range associated with $f$.

(ii)[3]

Find the value of the constant $k$ for which the equation $gf(x) = k$ has equal roots.

Worked solution & mark scheme

This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Find the turning point of $f(x)=4x-2x^2$ by taking $x=1$.” …

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