Mathematics 9709 · AS & A Level · Functions

Functions — practice question

The one-one function $f$ is given by $f : x \mapsto -3x^2 + 12x + 2$ for $x \leq k$.
(a)[2]

Write $-3x^2 + 12x + 2$ in the form $-3(x - a)^2 + b$, where $a$ and $b$ are constants.

(b)[1]

State the greatest possible value of the constant $k$.

(c)[1]

Now that $k = -1$ is given, state the range of $f$.

(d)[3]

Find an expression for $f^{-1}(x)$.

(e)[3]

After the graph of $y = f(x)$ is translated by $\begin{pmatrix}-3\\1\end{pmatrix}$, it becomes the graph of $y = g(x)$. Write $g(x)$ in the form $px^2 + qx + r$, where $p$, $q$ and $r$ are constants.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correct square form $-3(x-2)^2$

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