Question

rút gọn biểu thức sau:\(\sqrt{20}-\sqrt{45}+3\sqrt{18}+\sqrt{72}\)

Answer 1

\(\sqrt{20}-\sqrt{45}+3\sqrt{18}+\sqrt{72}\)

\(=\sqrt{4.5}-\sqrt{9.5}+3\sqrt{18}+\sqrt{4.18}\)

\(=2\sqrt{5}-3\sqrt{5}+3\sqrt{18}+2\sqrt{18}\)

\(=-\sqrt{5}+5\sqrt{18}\)

Answer 2

\(\sqrt{20}-\sqrt{45}+3\sqrt{18}+\sqrt{72}\)

\(=2\sqrt{5}-3\sqrt{5}+3\sqrt{18}+2\sqrt{18}\)

\(=-\sqrt{5}+5\sqrt{18}\)