Question 22

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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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