Question

If the three terms $15$, $x$ and$135$ are in proportion then what is the value of $x$

Answer 1

Given:$15,x,135$ are in proportion

$\Rightarrow \frac{15}{x}=\frac{x}{135}$

$\Rightarrow x^2=15\times 135$

$\Rightarrow x^2=5\times 3\times 5\times 3\times 3\times 3$

$\Rightarrow x=\sqrt{5\times 5\times 3\times 3\times 3\times 3}$

$\therefore x=5\times 3\times 3=45$