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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.

[2]
a.

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 \(g(x)\).

[4]
b.

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]

a.

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]

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Topic 2 - Core: Functions and equations » 2.3 » Transformations of graphs: translations; stretches; reflections in the axes.

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