ĐKx> 0
a) rútx gọn đk
M=\frac{\sqrt{x}+1}{\sqrt{x}-1}b)Để M=\sqrt{x}\Leftrightarrow \frac{\sqrt{x}+1}{\sqrt{x}-1}=\sqrt{x}\Leftrightarrow \frac{\sqrt{x}+1}{\sqrt{x}-1}=\frac{x-\sqrt{x}}{\sqrt{x}-1}\Rightarrow \sqrt{x}+1=x-\sqrt{x}\Leftrightarrow x-2\sqrt{x}-1=0
ra z tự lm nốt nhé !!!
c)M=\frac{\sqrt{x}+1}{\sqrt{x}-1}=\frac{\sqrt{x}-1+2}{\sqrt{x}-1}=1+\frac{2}{\sqrt{x}-1}
Theo bài ra : x\in N\Rightarrow \sqrt{x}-1\in Ư(2)
Mà x>0\Rightarrow \sqrt{x}-1>-1
Thay
+) \sqrt{x}-1=1\Rightarrow x=4(thoả mãn);M=3(thoả mãn )
+)\sqrt{x}-1=2\Rightarrow x=9(thoả mãn );M=2(thoả mãn )
vậy ........
~~~~~Amen~~~~~