Classify the following numbers as rational or irrational:

(i) 2 − $\sqrt{5}$

(ii) 3 + $\sqrt{23}$ − $\sqrt{23}$

(iii) $\dfrac{2\sqrt{7}}{7\sqrt{7}}$

(iv) $\dfrac{1}{\sqrt{2}}$

(v) 2π

Simplify the following expression:

$(3 + \sqrt{3}) (2 + \sqrt{2})$

Simplify the following expression:

$(\sqrt{5} + \sqrt{2})$ ²

Simplify the following expression:

$(\sqrt{5}$ - $\sqrt{2})$ $(\sqrt{5}$ + $\sqrt{2})$