Mathematics 9709 · AS & A Level · Functions

Functions — practice question

The function $f$ is given by $f(x) = 3 + 6x - 2x^2$ for $x \in \mathbb{R}$.
(a)[3]

Write $f(x)$ in the form $a - b(x - c)^2$, where $a$, $b$ and $c$ are constants, and state the range of $f$.

(b)[2]

A reflection in one of the axes, followed by a translation, takes the graph of $y = f(x)$ to the graph of $y = h(x)$. It is given that the graph of $y = h(x)$ has a minimum point at the origin. Give details of the reflection and translation involved.

(c)[2]

Sketch the graph of $y = g(x)$ and explain why $g$ is a one-one function. You do not need to determine the coordinates of any intersections with the axes.

(d)[4]

Sketch the graph of $y = g^{-1}(x)$ on your diagram in (c), and find an expression for $g^{-1}(x)$. You should label the two graphs in your diagram appropriately and show any relevant mirror line.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: Obtain $b=2$ together with $c=\tfrac32$

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