Question

Which numbers are irrational? Choose all answers that are correct.

Answer 1

The first two. In fact, you have

$\sqrt{20} = \sqrt{4\cdot 5} = \sqrt{4}\cdot \sqrt{5} = 2\sqrt{5}$

and $\sqrt{5}$ is irrational.

Similarly, $\pi$ is irrational, and the same goes for $4\pi$.

Instead, the square root and the second power simplify in the third option:

$\left(\sqrt{13}\right)^2 = 13$

and similarly,

$\sqrt{196} = \sqrt{14^2} = 14$