1.10: Completing the square and a modulus graph

0606/13/M/J/20 — Question 4 · 9 marks

(a)
Write 2x2+3x42x^{2} + 3x - 4 in the form a(x+b)2+ca(x + b)^{2} + c, where aa, bb and cc are constants.
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(b)
Hence write down the coordinates of the stationary point on the curve y=2x2+3x4y = 2x^{2} + 3x - 4.
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(c)
On the axes below, sketch the graph of y=2x2+3x4y = \left\lvert 2x^{2} + 3x - 4 \right\rvert, showing the exact values of the intercepts of the curve with the coordinate axes.
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(d)
Find the value of kk for which 2x2+3x4=k\left\lvert 2x^{2} + 3x - 4 \right\rvert = k has exactly 33 values of xx.
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