Solve |f(x)| compared to |g(x)| with parameters

Solve modulus equation or inequality where expressions contain a positive constant parameter a or k, giving answer in terms of that parameter.

18 questions · Standard +0.7

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CAIE P2 2020 March Q5
9 marks Standard +0.8
5
  1. Sketch, on the same diagram, the graphs of \(y = | x + 2 k |\) and \(y = | 2 x - 3 k |\), where \(k\) is a positive constant. Give, in terms of \(k\), the coordinates of the points where each graph meets the axes.
  2. Find, in terms of \(k\), the coordinates of each of the two points where the graphs intersect.
  3. Find, in terms of \(k\), the largest value of \(t\) satisfying the inequality $$\left| 2 ^ { t } + 2 k \right| \geqslant \left| 2 ^ { t + 1 } - 3 k \right| .$$
CAIE P2 2017 June Q1
3 marks Standard +0.3
1 Solve the equation \(| x + a | = | 2 x - 5 a |\), giving \(x\) in terms of the positive constant \(a\).
CAIE P3 2010 June Q1
4 marks Challenging +1.2
1 Solve the inequality \(| x + 3 a | > 2 | x - 2 a |\), where \(a\) is a positive constant.
CAIE P3 2014 June Q1
4 marks Standard +0.8
1 Find the set of values of \(x\) satisfying the inequality $$| x + 2 a | > 3 | x - a |$$ where \(a\) is a positive constant.
CAIE P3 2018 November Q1
4 marks Standard +0.8
1 Find the set of values of \(x\) satisfying the inequality \(2 | 2 x - a | < | x + 3 a |\), where \(a\) is a positive constant. [4]
CAIE P3 2022 June Q1
4 marks Challenging +1.2
1 Find, in terms of \(a\), the set of values of \(x\) satisfying the inequality $$2 | 3 x + a | < | 2 x + 3 a |$$ where \(a\) is a positive constant.
CAIE P3 2021 November Q2
4 marks Challenging +1.2
2 Solve the inequality \(| 3 x - a | > 2 | x + 2 a |\), where \(a\) is a positive constant.
Edexcel C3 2017 June Q6
8 marks Standard +0.3
  1. Given that \(a\) and \(b\) are positive constants,
    1. on separate diagrams, sketch the graph with equation
      1. \(y = | 2 x - a |\)
      2. \(y = | 2 x - a | + b\)
    Show, on each sketch, the coordinates of each point at which the graph crosses or meets the axes. Given that the equation $$| 2 x - a | + b = \frac { 3 } { 2 } x + 8$$ has a solution at \(x = 0\) and a solution at \(x = c\),
  2. find \(c\) in terms of \(a\).
Edexcel FP2 2005 June Q1
5 marks Standard +0.8
  1. Sketch the graph of \(y = | x - 2 a |\), given that \(a > 0\).
  2. Solve \(| x - 2 a | > 2 x + a\), where \(a > 0\).
    (3)(Total 5 marks)
Edexcel FP2 2009 June Q7
12 marks Challenging +1.2
  1. (a) Sketch the graph of \(y = \left| x ^ { 2 } - a ^ { 2 } \right|\), where \(a > 1\), showing the coordinates of the points where the graph meets the axes.
    (b) Solve \(\left| x ^ { 2 } - a ^ { 2 } \right| = a ^ { 2 } - x , a > 1\).
    (c) Find the set of values of \(x\) for which \(\left| x ^ { 2 } - a ^ { 2 } \right| > a ^ { 2 } - x , a > 1\).
Edexcel C34 2016 June Q6
9 marks Standard +0.3
6. Given that \(a\) and \(b\) are constants and that \(a > b > 0\)
  1. on separate diagrams, sketch the graph with equation
    1. \(y = | x - a |\)
    2. \(y = | x - a | - b\) Show on each sketch the coordinates of each point at which the graph crosses or meets the \(x\)-axis and the \(y\)-axis.
  2. Hence or otherwise find the complete set of values of \(x\) for which $$| x - a | - b < \frac { 1 } { 2 } x$$ giving your answer in terms of \(a\) and \(b\).
Edexcel PMT Mocks Q1
5 marks Standard +0.3
  1. Given that \(a\) is a positive constant,
    a. Sketch the graph with equation
$$y = | a - 2 x |$$ Show on your sketch the coordinates of each point at which the graph crosses the \(x\)-axis and \(y\)-axis.
b. Solve the inequality \(| a - 2 x | > x + 2 a\)
Edexcel Paper 2 2021 October Q11
10 marks Standard +0.8
11. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{6c32000f-574f-473c-bd04-9cfe2c1bd715-30_630_630_312_721} \captionsetup{labelformat=empty} \caption{Figure 4}
\end{figure} Figure 4 shows a sketch of the graph with equation $$y = | 2 x - 3 k |$$ where \(k\) is a positive constant.
  1. Sketch the graph with equation \(y = \mathrm { f } ( x )\) where $$f ( x ) = k - | 2 x - 3 k |$$ stating
    • the coordinates of the maximum point
    • the coordinates of any points where the graph cuts the coordinate axes
    • Find, in terms of \(k\), the set of values of \(x\) for which
    $$k - | 2 x - 3 k | > x - k$$ giving your answer in set notation.
  2. Find, in terms of \(k\), the coordinates of the minimum point of the graph with equation $$y = 3 - 5 f \left( \frac { 1 } { 2 } x \right)$$
Edexcel C3 Q3
8 marks Standard +0.3
3. The function \(f\) is defined by $$f : x \text { a } | 2 x - a | , \quad x \in ^ { \circ }$$ where \(a\) is a positive constant.
  1. Sketch the graph of \(y = \mathrm { f } ( x )\), showing the coordinates of the points where the graph cuts the axes.
  2. On a separate diagram, sketch the graph of \(y = \mathrm { f } ( 2 x )\), showing the coordinates of the points where the graph cuts the axes.
  3. Given that a solution of the equation \(\mathrm { f } ( x ) = \frac { 1 } { 2 } x\) is \(x = 4\), find the two possible values of \(a\).
Edexcel C3 Q5
13 marks Standard +0.8
5. The functions \(f\) and \(g\) are defined by $$\begin{aligned} & \mathrm { f } : x \alpha \quad | x - a | + a , x \in \mathbb { R } \\ & \mathrm {~g} : x \alpha \quad 4 x + a , \quad x \in \mathbb { R } \end{aligned}$$ where \(a\) is a positive constant.
  1. On the same diagram, sketch the graphs of f and g , showing clearly the coordinates of any points at which your graphs meet the axes.
  2. Use algebra to find, in terms of \(a\), the coordinates of the point at which the graphs of f and g intersect.
  3. Find an expression for \(\mathrm { fg } ( x )\).
  4. Solve, for \(x\) in terms of \(a\), the equation $$\mathrm { fg } ( x ) = 3 a$$ \section*{6.}
Edexcel C3 Q3
7 marks Standard +0.8
3. (a) Sketch the graph of \(y = | 2 x + a | , a > 0\), showing the coordinates of the points where the graph meets the coordinate axes.
(b) On the same axes, sketch the graph of \(y = \frac { 1 } { x }\).
(c) Explain how your graphs show that there is only one solution of the equation $$x | 2 x + a | - 1 = 0$$ (d) Find, using algebra, the value of \(x\) for which \(x | 2 x + 1 | - 1 = 0\).
Edexcel C3 Q7
8 marks Standard +0.3
7. The function \(f\) is defined by $$f : x \wp \rightarrow | 2 x - a | , x \in \mathbb { R }$$ where \(a\) is a positive constant.
  1. Sketch the graph of \(y = \mathrm { f } ( x )\), showing the coordinates of the points where the graph cuts the axes.
  2. On a separate diagram, sketch the graph of \(y = \mathrm { f } ( 2 x )\), showing the coordinates of the points where the graph cuts the axes.
  3. Given that a solution of the equation \(\mathrm { f } ( x ) = \frac { 1 } { 2 } x\) is \(x = 4\), find the two possible values of \(a\).
Edexcel FP2 Q7
12 marks Challenging +1.2
7. (a) Sketch the graph of \(y = \left| x ^ { 2 } - a ^ { 2 } \right|\), where \(a > 1\), showing the coordinates of the points where the graph meets the axes.
(b) Solve \(\left| x ^ { 2 } - a ^ { 2 } \right| = a ^ { 2 } - x , a > 1\).
(c) Find the set of values of \(x\) for which \(\left| x ^ { 2 } - a ^ { 2 } \right| > a ^ { 2 } - x , a > 1\).