EXM.1.AHL.TZ0.2

pestleMathematicsAIHLPaper 1EXM· ahl-1-14-introduction-to-matricessource ↗

If $A = \left( {\begin{array}{*{20}{c}} {2p}&3 \\ { - 4p}&p \end{array}} \right)$ and det $A = 14$ , find the possible values of $p$ .

Markscheme / solution

* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.

$2{p^2} + 12p = 14$ (M1)(A1)

${p^2} + 6p - 7 = 0$

$\left( {p + 7} \right)\left( {p - 1} \right) = 0$ (A1)

$p = - 7$ or $p = 1$ (A1) (C4)

Note: Both answers are required for the final (A1).

[4 marks]

Examiners’ report

[N/A]