Question

[chi mai Nguyen]

\(3\sqrt{20}-2\sqrt{45}+4\sqrt{5}.\)
\(\left(\sqrt{28}-2\sqrt{14}+\sqrt{7}\right)\sqrt{7}+7\sqrt{8}\)

\(3\sqrt{12}-4\sqrt{27}+5\sqrt{48}\)

\(\left(\sqrt{45}-2\sqrt{10}+\sqrt{5}\right)\sqrt{5}+5\sqrt{8}\)

Tính

Answer 1

[Phu Dang Gia]

\(3\sqrt{20}-2\sqrt{45}+4\sqrt{5}=6\sqrt{5}-6\sqrt{5}+4\sqrt{5}=4\sqrt{5}\)

\(\left(\sqrt{28}-2\sqrt{14}+\sqrt{7}\right)\sqrt{7}+7\sqrt{8}=\left(2\sqrt{7}-2\sqrt{2}.\sqrt{7}+\sqrt{7}\right)\sqrt{7}+7\sqrt{8}\)

\(=14-14\sqrt{2}+7+14\sqrt{2}=21\)

\(3\sqrt{12}-4\sqrt{27}+5\sqrt{48}=6\sqrt{3}-12\sqrt{3}+20\sqrt{3}=14\sqrt{3}\)

câu tiếp tương tự câu thứ 2 nha