Date | May 2014 | Marks available | 4 | Reference code | 14M.1.hl.TZ2.8 |
Level | HL only | Paper | 1 | Time zone | TZ2 |
Command term | Find | Question number | 8 | Adapted from | N/A |
Question
The function f is defined by
\[f(x) = \left\{ \begin{array}{r}1 - 2x,\\{\textstyle{3 \over 4}}{(x - 2)^2} - 3,\end{array} \right.\begin{array}{*{20}{c}}{x \le 2}\\{x > 2}\end{array}\]
Determine whether or not \(f\)is continuous.
The graph of the function \(g\) is obtained by applying the following transformations to the graph of \(f\):
a reflection in the \(y\)–axis followed by a translation by the vector \(\left( \begin{array}{l}2\\0\end{array} \right)\).
Find \(g(x)\).
Markscheme
\(1 - 2(2) = - 3\) and \(\frac{3}{4}{(2 - 2)^2} - 3 = - 3\) A1
both answers are the same, hence f is continuous (at \(x = 2\)) R1
Note: R1 may be awarded for justification using a graph or referring to limits. Do not award A0R1.
[2 marks]
reflection in the y-axis
\(f( - x) = \left\{ \begin{array}{r}1 + 2x,\\{\textstyle{3 \over 4}}{(x + 2)^2} - 3,\end{array} \right.\begin{array}{*{20}{c}}{x \ge - 2}\\{x < - 2}\end{array}\) (M1)
Note: Award M1 for evidence of reflecting a graph in y-axis.
translation \(\left( \begin{array}{l}2\\0\end{array} \right)\)
\(g(x) = \left\{ \begin{array}{r}2x - 3,\\{\textstyle{3 \over 4}}{x^2} - 3,\end{array} \right.\begin{array}{*{20}{c}}{x \ge 0}\\{x < 0}\end{array}\) (M1)A1A1
Note: Award (M1) for attempting to substitute \((x - 2)\) for x, or translating a graph along positive x-axis.
Award A1 for the correct domains (this mark can be awarded independent of the M1).
Award A1 for the correct expressions.
[4 marks]