Question

Rút gọn \(A=\left(2\sqrt{2}-\sqrt{5}+3\sqrt{2}\right)\left(\sqrt{18}-\sqrt{20}+2\sqrt{2}\right)\)

Answer 1

\(A=\left(2\sqrt{2}-\sqrt{5}+3\sqrt{2}\right)\left(\sqrt{18}-\sqrt{20}+2\sqrt{2}\right)\)

\(A=\left(2\sqrt{2}-\sqrt{5}+3\sqrt{2}\right)\left(\sqrt{9.2}-\sqrt{2^2.5}+2\sqrt{2}\right)\)

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

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

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

\(A=50-10\sqrt{10}-5\sqrt{10}+10\)

\(A=60-5\sqrt{10}\)

Chúc bạn học tốt!!!