1.3: Completing the square and a modulus graph

0606/11/O/N/18 — Question 4 · 7 marks

(i)
Write x29x+8x^{2} - 9x + 8 in the form (xp)2q(x - p)^{2} - q, where pp and qq are constants.
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(ii)
Hence write down the coordinates of the minimum point on the curve y=x29x+8y = x^{2} - 9x + 8.
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(iii)
On the axes below, sketch the graph of y=x29x+8y = \left\lvert x^{2} - 9x + 8 \right\rvert, showing the coordinates of the points where the curve meets the coordinate axes.
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(iv)
Write down the value of kk for which x29x+8=k\left\lvert x^{2} - 9x + 8 \right\rvert = k has exactly 3 solutions.
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