Question

căn 16b + 2 căn 40b - 3 căn 90b

mọi người giúp mik với ạ 

Answer 1

\(\sqrt{16b}+2\sqrt{40b}-3\sqrt{90b}\\ =4\sqrt{b}+4\sqrt{10b}-9\sqrt{10b}\\ =4\sqrt{b}-5\sqrt{10b}=\sqrt{b}\left(4-5\sqrt{10}\right)\)

Answer 2

\(\sqrt{16b}+2\sqrt{40b}-3\sqrt{90b}\left(đk:x\ge0\right)\)

\(=4\sqrt{b}+4\sqrt{10b}-9\sqrt{10b}\)

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

Answer 3

\(\sqrt{16b}+2\sqrt{40b}-3\sqrt{90b}\)

\(=4\sqrt{b}+4\sqrt{10b}-9\sqrt{10b}\)

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