waecmaths question:
Given that $(2x-1)(x+5)=2{{x}^{2}}-mx-5$, what is the value of m?
Option A:
11
Option B:
5
Option C:
–9
Option D:
10
waecmaths solution:
$\begin{align} & (2x-1)(x+5)=2{{x}^{2}}-mx-5 \\ & 2{{x}^{2}}+10x-x-5=2{{x}^{2}}-mx-5 \\ & 2{{x}^{2}}+9x-5=2{{x}^{2}}-mx-5 \\ & \text{Comparing terms} \\ & 9x=-mx \\ & m=-9 \\\end{align}$
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