Edexcel FP1 2022 June — Question 7

Exam BoardEdexcel
ModuleFP1 (Further Pure Mathematics 1)
Year2022
SessionJune
TopicInequalities

7. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{7de3f581-eff1-4671-87a9-55ca1bb97890-20_591_962_312_548} \captionsetup{labelformat=empty} \caption{Figure 1}
\end{figure} Figure 1 shows a sketch of the curve with equation \(y = \left| x ^ { 2 } - 8 \right|\) and a sketch of the straight line with equation \(y = m x + c\), where \(m\) and \(c\) are positive constants. The equation $$\left| x ^ { 2 } - 8 \right| = m x + c$$ has exactly 3 roots, as shown in Figure 1.
  1. Show that $$m ^ { 2 } - 4 c + 32 = 0$$ Given that \(c = 3 m\)
  2. determine the value of \(m\) and the value of \(c\)
  3. Hence solve $$\left| x ^ { 2 } - 8 \right| \geqslant m x + c$$