waecmaths question:
Simplify $\left( \frac{10\sqrt{3}}{\sqrt{5}}-\sqrt{15} \right)$
Option A:
75.00
Option B:
15.00
Option C:
8.66
Option D:
3.87
waecmaths solution:
$\begin{align} & {{\left( \frac{10\sqrt{3}}{\sqrt{5}}-\sqrt{15} \right)}^{2}}={{\left( \frac{10\sqrt{3}-\sqrt{75}}{\sqrt{5}} \right)}^{2}} \\ & {{\left( \frac{10\sqrt{3}}{\sqrt{5}}-\sqrt{15} \right)}^{2}}={{\left( \frac{10\sqrt{3}-5\sqrt{3}}{\sqrt{5}} \right)}^{2}} \\ & {{\left( \frac{10\sqrt{3}}{\sqrt{5}}-\sqrt{15} \right)}^{2}}={{\left( \frac{5\sqrt{3}}{\sqrt{5}} \right)}^{2}}=\frac{25\times 3}{5} \\ & {{\left( \frac{10\sqrt{3}}{\sqrt{5}}-\sqrt{15} \right)}^{2}}=15 \\\end{align}$
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