Question

[Nguyễn Ngọc Hiền]

Rut gon A = \(\sqrt{16b}+2\sqrt{40b}-3\sqrt{90b}va`b\ge0\)

Answer 1

[Đinh Thùy Linh]

\(A=\sqrt{4^2b}+2\sqrt{2^2\cdot10b}-3\sqrt{3^2\cdot10b}=4\sqrt{b}+4\sqrt{10}\cdot\sqrt{b}-9\sqrt{10}\cdot\sqrt{b}\)

\(=4\sqrt{b}-5\sqrt{10}\sqrt{b}=\left(4-5\sqrt{10}\right)\sqrt{b}\)

Answer 2

[o0o Dem_Ngay _Xa __Em o0o]

Rut gon A = √16b+2√40b−3√90bva`b≥0

 A=√42b+2√22·10b−3√32·10b=4√b+4√10·√b−9√10·√b

=4√b−5√10√b=(4−5√10)√b