Sketch y=|f(x)| or y=f(|x|) for non-linear f(x) and solve

Sketch graphs involving modulus applied to quadratic or other non-linear functions (e.g. y = |x²-2ax|, y = 8+2|x|-x²), showing axis intercepts and stationary points, and solve related equations or inequalities.

6 questions · Standard +0.6

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Edexcel P3 2022 January Q7
10 marks Standard +0.3
7. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{f3272b4c-d8dc-4f32-add9-153de90f4d0a-18_720_746_210_591} \captionsetup{labelformat=empty} \caption{Figure 2}
\end{figure} Figure 2 shows a sketch of part of the graph with equation \(y = \mathrm { f } ( x )\), where $$f ( x ) = \frac { 1 } { 2 } | 2 x + 7 | - 10$$
  1. State the coordinates of the vertex, V, of the graph.
  2. Solve, using algebra, $$\frac { 1 } { 2 } | 2 x + 7 | - 10 \geqslant \frac { 1 } { 3 } x + 1$$
  3. Sketch the graph with equation $$y = | \mathrm { f } ( x ) |$$ stating the coordinates of the local maximum point and each local minimum point.
Edexcel AEA 2017 Specimen Q2
11 marks Challenging +1.8
2.(a)On separate diagrams,sketch the curves with the following equations.On each sketch you should label the exact coordinates of the points where the curve meets the coordinate axes.
  1. \(y = 8 + 2 x - x ^ { 2 }\)
  2. \(y = 8 + 2 | x | - x ^ { 2 }\)
  3. \(y = 8 + x + | x | - x ^ { 2 }\) (b)Find the values of \(x\) for which $$\left| 8 + x + | x | - x ^ { 2 } \right| = 8 + 2 | x | - x ^ { 2 }$$
AQA C3 2008 January Q7
12 marks Standard +0.3
7
  1. Describe a sequence of two geometrical transformations that maps the graph of \(y = x ^ { 2 }\) onto the graph of \(y = 4 x ^ { 2 } - 5\).
  2. Sketch the graph of \(y = \left| 4 x ^ { 2 } - 5 \right|\), indicating the coordinates of the point where the curve crosses the \(y\)-axis.
    1. Solve the equation \(\left| 4 x ^ { 2 } - 5 \right| = 4\).
    2. Hence, or otherwise, solve the inequality \(\left| 4 x ^ { 2 } - 5 \right| \geqslant 4\).
AQA C3 2009 June Q4
12 marks Standard +0.3
4
  1. Sketch the graph of \(y = \left| 50 - x ^ { 2 } \right|\), indicating the coordinates of the point where the graph crosses the \(y\)-axis.
  2. Solve the equation \(\left| 50 - x ^ { 2 } \right| = 14\).
  3. Hence, or otherwise, solve the inequality \(\left| 50 - x ^ { 2 } \right| > 14\).
  4. Describe a sequence of two geometrical transformations that maps the graph of \(y = x ^ { 2 }\) onto the graph of \(y = 50 - x ^ { 2 }\).
Edexcel C3 Q7
12 marks Standard +0.3
7. The function f is defined by $$\mathrm { f } ( x ) \equiv x ^ { 2 } - 2 a x , \quad x \in \mathbb { R } ,$$ where \(a\) is a positive constant.
  1. Showing the coordinates of any points where each graph meets the axes, sketch on separate diagrams the graphs of
    1. \(\quad y = | \mathrm { f } ( x ) |\),
    2. \(y = \mathrm { f } ( | x | )\). The function g is defined by $$\mathrm { g } ( x ) \equiv 3 a x , \quad x \in \mathbb { R } .$$
  2. Find fg(a) in terms of \(a\).
  3. Solve the equation $$\operatorname { gf } ( x ) = 9 a ^ { 3 }$$
Edexcel PURE 2024 October Q3
Standard +0.8
3. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{b9472037-c143-4b68-86e2-801f71029773-06_638_643_251_712} \captionsetup{labelformat=empty} \caption{Figure 2}
\end{figure} In this question you must show all stages of your working. Solutions relying entirely on calculator technology are not acceptable.
Figure 2 shows a sketch of the curve with equation \(y = \mathrm { f } ( x )\), where $$f ( x ) = 2 x ^ { 2 } - 10 x \quad x \in \mathbb { R }$$
  1. Solve the equation $$\mathrm { f } ( | x | ) = 48$$
  2. Find the set of values of \(x\) for which $$| f ( x ) | \geqslant \frac { 5 } { 2 } x$$