Toán 9?

[cold_noodles]

1. cho M = \[\frac{4}{\sqrt{a} -1}\] \[+\frac{1}{\sqrt{a}+a}\] \[-\frac{a+1}{\sqrt{a}}\]
a rút gọn
b tìm a để M >2
2.M= \[( 1-\frac{\sqrt{a}}{1+\sqrt{a}})\] \[\frac{\sqrt{a}-1}{\sqrt{a}-2}\] \[-\frac{\sqrt{a}+2}{\sqrt{a}+1}\] \[-\frac{\sqrt{a}+2}{a-2-\sqrt{a}})\]
a rút gọn
b tìm a để M>-1

 

[Aquarius]

Bài 1:
a. quy đồng ta có:
\[=\frac{4\sqrt{a}(\sqrt{a}+1)}{\sqrt{a}(a-1)} + \frac{\sqrt{a}-1}{\sqrt{a}(a-1)} - \frac{(a+1)(a-1)}{\sqrt{a}(a-1)}\]
\[= \frac{4a +5\sqrt{a}-{a}^{2}}{\sqrt{a}-1}\]
\[= \frac{4\sqrt{a}+5-a\sqrt{a}}{a-1}\]