(viii) $(2-3\sqrt{5})$
Let us assume that $(2-3\sqrt{5})$ is rational.
subtract given numbers from 2 , considering 2 is rational number.
as we know , difference of two rational numbers is rational
$2-(2-3\sqrt{5})$is rational.
$\Rightarrow 3\surd 5$ is rational
above result is possible if 3is rational and $\surd 5$ is rational.
Because , product of two rational numbers is rational.
but the fact is $\mathrm{\surd }5$ is an irrational.
Our assumption is wrong, and $(2-3\sqrt{5})$ is irrational