Question

[pansak9]

Tính gtri biểu thức:

a, A = \(\sqrt{\left(2-\sqrt{5}\right)^2}\) + \(\sqrt{\left(2\sqrt{5}-\sqrt{5}\right)^2}\)

b, B = \(\sqrt{\left(7-2\sqrt{2}\right)^2}\) + \(\sqrt{\left(3-2\sqrt{2}\right)^2}\)

Answer 1

[Ngô Hải Nam]

a)

\(A=\sqrt{\left(2-\sqrt{5}\right)^2}+\sqrt{\left(2\sqrt{5}-\sqrt{5}\right)^2}\)

\(=\left|2-\sqrt{5}\right|+\left|2\sqrt{5}-\sqrt{5}\right|\)

\(=\sqrt{5}-2+2\sqrt{5}-\sqrt{5}\) (vì \(2-\sqrt{5}< 0;2\sqrt{5}-\sqrt{5}>0\) )

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

b)

\(B=\sqrt{\left(7-2\sqrt{2}\right)^2}+\sqrt{\left(3-2\sqrt{2}\right)^2}\)

\(=\left|7-2\sqrt{2}\right|+\left|3-2\sqrt{2}\right|\)

\(=7-2\sqrt{2}+3-2\sqrt{2}\) ( vì \(7-2\sqrt{2}>0;3-2\sqrt{2}>0\) )

\(=10-4\sqrt{2}\)

Answer 2

[⭐Hannie⭐]

Ôi ngầu wa:)) Học vượt lớp r hả:))