| Exam Board | Edexcel |
| Module | P1 (Pure Mathematics 1) |
| Year | 2018 |
| Session | Specimen |
| Topic | Inequalities |
5. (a) On the same axes, sketch the graphs of \(y = x + 2\) and \(y = x ^ { 2 } - x - 6\) showing the coordinates of all points at which each graph crosses the coordinate axes.
(b) On your sketch, show, by shading, the region \(R\) defined by the inequalities
$$y < x + 2 \text { and } y > x ^ { 2 } - x - 6$$
(c) Hence, or otherwise, find the set of values of \(x\) for which \(x ^ { 2 } - 2 x - 8 < 0\)
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Quadratic: \(y = x ^ { 2 } - x - 6 = ( x - 3 ) ( x + 2 )\)
$$x = 3 , \quad x = - 2 @ y = 0$$
Linear: \(\quad y = x + 2\)
$$\begin{array} { l l }
x = 0 : & y = 2 \quad ( 0,2 )
y = 0 : & x = - 2 \quad ( - 2,0 )
\end{array}$$
c) \(\quad x ^ { 2 } - 2 x - 8 < 0\)
$$\begin{aligned}
\therefore ( x - 4 ) ( x + 2 ) & < 0
x = 4 \quad x = - 2 &
\therefore - 2 < x < 4 & < 4
\end{aligned}$$