Question 11

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waecmaths question: 

Adding 42 to a given positive number gives the same result as squaring the number. Find the number.  

Option A: 

14

Option B: 

13

Option C: 

7

Option D: 

6

waecmaths solution: 

$\begin{align}  & \text{Let the positive number be }a \\ & 42+a={{a}^{2}} \\ & {{a}^{2}}-a-42=0 \\ & (a-7)(a+6)=0 \\ & a=7\text{ or }a=-6\text{  (Ignore }a=-6) \\ & a=7 \\\end{align}$

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