Question:
Simplify the following expressions:
(i) $(4+\sqrt{7})(3+\sqrt{2})$
(ii) $(3+\sqrt{3})(5-\sqrt{2})$
(iii) $(\sqrt{5}-2)(\sqrt{3}-\sqrt{5})$
Solution:
(i) $(4+\sqrt{7})(3+\sqrt{2})$
$=12+4 \sqrt{2}+3 \sqrt{7}+\sqrt{7 \times 2}$
$=12+4 \sqrt{2}+3 \sqrt{7}+\sqrt{14}$
(ii) $(3+\sqrt{3})(5-\sqrt{2})$
$=\sqrt{15}-3 \sqrt{2}+5 \sqrt{3}-\sqrt{3 \times 2}$
$=\sqrt{15}-3 \sqrt{2}+5 \sqrt{3}-\sqrt{6}$
(iii) $(\sqrt{5}-2)(\sqrt{3}-\sqrt{5})$
$=\sqrt{15}-\sqrt{25}-2 \sqrt{3}+2 \sqrt{5}$
$=\sqrt{15}-\sqrt{5 \times 5}-2 \sqrt{3}+2 \sqrt{5}$
$=\sqrt{15}-5-2 \sqrt{3}+2 \sqrt{5}$