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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