waecmaths question:
Solve the equation ${{2}^{7}}={{8}^{5-x}}$
Option A:
$\tfrac{5}{8}$
Option B:
$\tfrac{8}{3}$
Option C:
$\tfrac{3}{2}$
Option D:
$\tfrac{15}{4}$
waecmaths solution:
$\begin{align} & {{2}^{7}}={{2}^{3(5-x)}} \\ & {{2}^{7}}={{2}^{15-3x}} \\ & \text{Equating the powers since the bases are equal} \\ & 7=15-3x \\ & 3x=8 \\ & x=\frac{8}{3} \\\end{align}$
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