Đáp án:
\(a)A=\sqrt{100x^2(y-1)^2}\)
\(A=\sqrt{[10x(y-1)]^2}\)
\(A=|10x(y-1)|\)
Vì \(x>y>1\Rightarrow x>0,y-1>0\)
\(\Rightarrow x(y-1)>0\)
\(\Rightarrow 10x(y-1)>0\)
\(\Rightarrow A=10x(y-1)\)
\(b)B=\sqrt{\dfrac{(a-b)^2}{5(a-\sqrt{ab})}}(a>0,b>0,a \ne b)\)
\(B=\sqrt{\dfrac{[(\sqrt{a}-\sqrt{b})(\sqrt{a}+\sqrt{b})]^2}{\sqrt{a}(\sqrt{a}-\sqrt{b})}}\)
\(B=\sqrt{\dfrac{(\sqrt{a}-\sqrt{b})(\sqrt{a}+\sqrt{b})^2}{\sqrt{a}}}\)
\(B=(\sqrt{a}+\sqrt{b})\sqrt{\dfrac{\sqrt{a}-\sqrt{b}}{\sqrt{a}}}\)
