Question

Rút gọn biểu thức A= (1-\(\dfrac{4}{x}\))(\(\dfrac{x-1}{x+3\sqrt{x}+2}\)-\(\dfrac{\sqrt{x}+1}{\sqrt{x}-2}\)) với x≥0 ; x≠4

Answer 1

\(A=\dfrac{x-4}{x}\cdot\left(\dfrac{\sqrt{x}-1}{\sqrt{x}+2}-\dfrac{\sqrt{x}+1}{\sqrt{x}-2}\right)\)

\(=\dfrac{x-4}{x}\cdot\dfrac{x-3\sqrt{x}+2-x-3\sqrt{x}-2}{x-4}=\dfrac{-6}{\sqrt{x}}\)