Figure 1 shows the graph of $y = f(x)$, $x \in \mathbb{R}$.\nThe graph consists of two line segments that meet at the point $P$.\nThe graph cuts the $y$-axis at the point $Q$ and the $x$-axis at the points $(-3, 0)$ and $R$.\nSketch, on separate diagrams, the graphs of\n(a) $y = |f(cx)|$\n(b) $y = f(-x)$\nGiven that $f(x) = 2 - |x + 1|$,\n(c) find the coordinates of the points $P$, $Q$ and $R$.\n(d) solve $f(x) = \frac{1}{2} x$. - Edexcel - A-Level Maths Pure - Question 4 - 2008 - Paper 5
Question 4
Figure 1 shows the graph of $y = f(x)$, $x \in \mathbb{R}$.\nThe graph consists of two line segments that meet at the point $P$.\nThe graph cuts the $y$-axis at the ... show full transcript
Worked Solution & Example Answer:Figure 1 shows the graph of $y = f(x)$, $x \in \mathbb{R}$.\nThe graph consists of two line segments that meet at the point $P$.\nThe graph cuts the $y$-axis at the point $Q$ and the $x$-axis at the points $(-3, 0)$ and $R$.\nSketch, on separate diagrams, the graphs of\n(a) $y = |f(cx)|$\n(b) $y = f(-x)$\nGiven that $f(x) = 2 - |x + 1|$,\n(c) find the coordinates of the points $P$, $Q$ and $R$.\n(d) solve $f(x) = \frac{1}{2} x$. - Edexcel - A-Level Maths Pure - Question 4 - 2008 - Paper 5
Step 1
Sketch the graph of $y = |f(cx)|$
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Answer
To sketch the graph of y=∣f(cx)∣, determine the function f(cx). If we assume c=1, the graph is similar to f(x) but reflected on the x-axis. Ensure to mark the y-intercepts and the peaks correctly.
Step 2
Sketch the graph of $y = f(-x)$
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Answer
The graph of y=f(−x) will reflect f(x) across the y-axis. Identify the new coordinates of the peaks and intercepts based on the original graph, ensuring all aspects like symmetry are considered.
Step 3
find the coordinates of the points $P$, $Q$ and $R$
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Answer
To find the coordinates of the points:\n- Point P: analyze the linear equations given for f(x). The intersection will be (−1,2).\n- Point Q: substitute x=0 into f(x), yielding Q(0,1).\n- Point R: it will be located at (1,0) based on the x-intercept.
Step 4
solve $f(x) = \frac{1}{2} x$
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Answer
Set 2−∣x+1∣=21x:\n1. For x≥−1: derive 2−(x+1)=21x, leading to x=−6. \n2. For x<−1: derive 2−(−x−1)=21x, yielding x=3.\nCombine solutions: x=−6 is the only valid solution in this case.