Question

giúp em câu 15.16 rút gọn biểu thức với ạ

 

Answer 1

15. \(=\dfrac{x-1-4\left(\sqrt{x}-1\right)+1}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}.\dfrac{x-1}{\sqrt{x}\left(\sqrt{x}-2\right)}\\ =\dfrac{x-4\sqrt{x}+4}{x-1}.\dfrac{x-1}{\sqrt{x}\left(\sqrt{x}-2\right)}\\ =\left(\sqrt{x}-2\right)^2.\dfrac{1}{\sqrt{x}\left(\sqrt{x}-2\right)}=\dfrac{\sqrt{x}-2}{\sqrt{x}}\)