Question

What is the smallest values of $x$ such that the expression represent a natual number?

$\sqrt{x^2-9}$

Answer 1

given, $\sqrt{x^2-9}$

when we take $x=5$ we get a perfect square,

$\Rightarrow \sqrt{5^2-3^2}$

$=\sqrt{25-9}$

$=\sqrt{16}$

$=4$

Therefore the answer is 5.