Question 12

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waecmaths question: 

Find the truth set of the equation ${{x}^{2}}=3(2x+9)$

Option A: 

$\{x:x=3,x=9\}$

Option B: 

$\{x:x=-3,x=-9\}$

Option C: 

$\{x:x=3,x=-9\}$

Option D: 

$\{x:x=-3,x=9\}$

waecmaths solution: 

$\begin{align}  & {{x}^{2}}=3(2x+9) \\ & {{x}^{2}}-6x-27=0 \\ & x(x-9)+3(x-9)=0 \\ & (x+3)(x-9)=0 \\ & \{x:x=-3,x=9\} \\\end{align}$

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