Mathematics 9709 · AS & A Level · Functions

Functions — practice question

The mapping $f$ is defined, for $x \in \mathbb{R}$, by $f: x \mapsto 2x^2 - 6x + 5$.
(i)[3]

Find the set of $p$ values for which the equation $f(x) = p$ has no real roots.

(ii)[3]

For $0 \leq x \leq 4$, the function $g$ is defined by $g: x \mapsto 2x^2 - 6x + 5$. Write $g(x)$ in the form $a(x + b)^2 + c$, where $a$, $b$ and $c$ are constants.

(iii)[2]

Find the range attained by $g$.

(iv)[1]

For $k \leq x \leq 4$, the function $h$ is defined by $h: x \mapsto 2x^2 - 6x + 5$, where $k$ is a constant. State the least value of $k$ for which $h$ has an inverse.

(v)[3]

For this value of $k$, give an expression for $h^{-1}(x)$.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: Rewrites as $2x^2-6x+5-p=0$

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