\(P=\left(\frac{\sqrt{a}}{\sqrt{ab}-b}+\frac{2\sqrt{a}-\sqrt{b}}{\sqrt{ab}-a}\right):\left(\frac{1}{b\sqrt{a}}-\frac{1}{a\sqrt{b}}\right)\)
1)chung minh \(P=\sqrt{ab}\)
2) tinh gia tri cua P khi \(a=3-\sqrt{5}\) va b=0,5
3) ting gia tri lon nhat cua P neu \(a^2+4b^2=8\)