$\sqrt{2}-3$

$-\sqrt{2}-3$

$\sqrt{2}+3$

$3-\sqrt{2}$

$b^2·b^3=b^6$

${\left(a^2\right)}^3=a^6$

$-a^2÷a=a$

${\left(a^3\right)}^2·a=a^6$

$\sqrt{16}=\pm 4$

$\sqrt[3]{-8}=2$

$-a\sqrt{\frac{1}{a}}=\sqrt{-a}$

$-\sqrt{64}=-8$