đk:x\(\ge0\)
để \(\frac{4}{\sqrt{x}+1}\in Z\)
thì \(\sqrt{x}+1\inƯ\left(4\right)=\left\{\pm1;\pm2;\pm4\right\}\)
Mà \(\sqrt{x}\ge0\Leftrightarrow\sqrt{x}+1\ge1\)
\(\Rightarrow\sqrt{x}+1\in\left\{1;2;4\right\}\)
ta có bảng
\(\sqrt{x}+1\) | 1 | 2 | 4 |
x | 0(TM) | 1(TM) | 9(TM) |