Đề: $\frac{2}{1-\sqrt{a}}$=9
Điều kiện:a≥0; a≠1
⇔$\frac{2}{1-\sqrt{a}}$-9=0
⇔$\frac{2}{1-\sqrt{a}}$-$\frac{9.(1-\sqrt{a})}{1-\sqrt{a}}$=0
⇔$\frac{2-9+9\sqrt{a}}{1-\sqrt{a}}$-=0
⇔-7+9$\sqrt{a}$ =0
⇔9$\sqrt{a}$=7
⇔$\sqrt{a}$=$\frac{7}{9}$
⇔a=($\frac{7}{9}$ )²
⇔a=$\frac{49}{81}$
#NOCOPY
#NOPLAGIARISM