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If $3^{x}=5$, the value of $3^{x+2}$ is

$10$
$25$
$2187$
$14$
$45$

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Official solution

Using exponent laws, $3^{x+2} = 3^x \cdot 3^2 = 3^x \cdot 9$.

Since $3^x=5$, then $3^{x+2} = 3^x \cdot 9 = 5 \cdot 9 = 45$.

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.