Question

Simplify the following expression :

ii) $(5+\sqrt{7})(5-\sqrt{7})$

Answer 1

Given : $(5+\sqrt{7})(5-\sqrt{7})$

Using identity, $(a-b)(a+b)=a^2-b^2$

$=5^2-(\sqrt{7}{)}^2$

$=25-7$

$=18$