Question

tính \(\sqrt{5}\times\sqrt{30}\times\sqrt{42.28}\)

Answer 1

\(\sqrt{5}.\sqrt{30}.\sqrt{42.28}\)

=\(\sqrt{5}.\sqrt{5.6}.\sqrt{6.7.7.4}\)

=\(5.6.7.2=420\)

Answer 2

\(\sqrt{5}.\sqrt{30}.\sqrt{42.28}=\sqrt{5}.\left(\sqrt{5}.\sqrt{6}\right).\left[\left(\sqrt{6}.\sqrt{7}\right).\left(\sqrt{7}.\sqrt{4}\right)\right]\)

\(=\left(\sqrt{5}.\sqrt{5}\right).\left(\sqrt{6}.\sqrt{6}\right).\left(\sqrt{7}.\sqrt{7}\right).\sqrt{4}\)

\(=5.6.7.2=\left(5.2\right).\left(6.7\right)=10.42=420\)

Có chỗ nào cậu không hiểu thì tớ sẽ giải thích