Question 45

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waecmaths question: 

If the sum of the roots of the equation $(x-p)(2x+1)=0$ is 1. find the value of p

Option A: 

$1\tfrac{1}{2}$

Option B: 

$\tfrac{1}{2}$

Option C: 

$-\tfrac{1}{2}$ 

Option D: 

$-1\tfrac{1}{2}$

waecmaths solution: 

$\begin{align}  & (x-p)(2x+1)=0 \\ & 2{{x}^{2}}+x-2px-p=0 \\ & 2{{x}^{2}}+(1-2p)x-p=0 \\ & {{x}^{2}}+\frac{(1-2p)}{2}x-\frac{p}{2}=0 \\ & \text{Sum of roots } \\ & \frac{1-2p}{2}=1 \\ & 1-2p=2 \\ & p=-\frac{1}{2} \\\end{align}$

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