Edexcel P1 2021 October — Question 8

Exam BoardEdexcel
ModuleP1 (Pure Mathematics 1)
Year2021
SessionOctober
TopicCurve Sketching
TypeCompleting square from standard form

8. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{f1e1d4f5-dd27-4839-a6f3-f6906666302c-22_657_659_214_646} \captionsetup{labelformat=empty} \caption{Figure 4}
\end{figure} Figure 4 shows a sketch of the curve \(C\) with equation $$y = 4 + 12 x - 3 x ^ { 2 }$$ The point \(M\) is the maximum turning point on \(C\).
    1. Write \(4 + 12 x - 3 x ^ { 2 }\) in the form $$a + b ( x + c ) ^ { 2 }$$ where \(a , b\) and \(c\) are constants to be found.
    2. Hence, or otherwise, state the coordinates of \(M\). The line \(l _ { 1 }\) passes through \(O\) and \(M\), as shown in Figure 4.
      A line \(l _ { 2 }\) touches \(C\) and is parallel to \(l _ { 1 }\)
  1. Find an equation for \(l _ { 2 }\)