Question

Answer 1

1: \(x=\dfrac{23\left(5-\sqrt{2}\right)}{5+\sqrt{2}}=\left(5-\sqrt{2}\right)^2\)

Thay \(x=\left(5-\sqrt{2}\right)^2\) vao B, ta duoc:

\(B=\dfrac{5-\sqrt{2}+2}{5-\sqrt{2}-5}=\dfrac{7-\sqrt{2}}{-\sqrt{2}}\)

2: \(A=\dfrac{x+3\sqrt{x}+\sqrt{x}+5}{x-25}\)

\(=\dfrac{x+4\sqrt{x}+5}{x-25}\)

Answer 2

1) \(x=\dfrac{23\left(5-\sqrt{2}\right)}{5+\sqrt{2}}=\dfrac{23\left(5-\sqrt{2}\right)^2}{5^2-2}=\left(5-\sqrt{2}\right)^2\)

\(\Rightarrow B=\dfrac{\sqrt{\left(5-\sqrt{2}\right)^2}+2}{\sqrt{\left(5-\sqrt{2}\right)^2}-5}\)

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

\(=\dfrac{\sqrt{2}-7}{\sqrt{2}}\)

\(=\dfrac{2-7\sqrt{2}}{2}\)