Question

(√5+2√2).(√5-2√2)

Answer 1

\(\left(\sqrt{5}+2\sqrt{2}\right)\left(\sqrt{5}-2\sqrt{2}\right)=5-8=-3\)

Answer 2

\(\left(\sqrt{5}+2\sqrt{2}\right)\left(\sqrt{5}-2\sqrt{2}\right)=\left(\sqrt{5}\right)^2-\left(2\sqrt{2}\right)^2=5-8=-3\)

Answer 3

\(\left(\sqrt{5}+2\sqrt{2}\right)\left(\sqrt{5}-2\sqrt{2}\right)\)

\(=\left(\sqrt{5}\right)^2-\left(2\sqrt{2}\right)^2\)

\(=5-8\)

\(=-3\)