Rút gọn biểu thức N
Giải thích
1) N = \(\frac{{\sqrt x - 1}}{{\sqrt x + 2}} + \frac{{5\sqrt x - 2}}{{x - 4}}\) = \(\frac{{(\sqrt x - 1)(\sqrt x - 2)}}{{(\sqrt x + 2)(\sqrt x - 2)}} + \frac{{5\sqrt x - 2}}{{(\sqrt x + 2)(\sqrt x - 2)}}\) = \(\frac{{x + 2\sqrt x }}{{(\sqrt x + 2)(\sqrt x - 2)}}\)
= \(\frac{{\sqrt x (\sqrt x + 2)}}{{(\sqrt x + 2)(\sqrt x - 2)}} = \frac{{\sqrt x }}{{\sqrt x - 2}}\)