Question

rút gọn
P= \((\dfrac{1-a\sqrt{a}}{1-\sqrt{a}}+\sqrt{a}).(\dfrac{1-\sqrt{a}}{1-a})^2\)

Answer 1

Với \(\left\{{}\begin{matrix}a\ge0\\a\ne1\end{matrix}\right.\)

\(P=\left(\dfrac{1-a\sqrt{a}}{1-\sqrt{a}}+\sqrt{a}\right).\left(\dfrac{1-\sqrt{a}}{1-a}\right)^2\\ =\left(\dfrac{\left(1-\sqrt{a}\right)\left(1+\sqrt{a}+a\right)}{1-\sqrt{a}}+\sqrt{a}\right).\left(\dfrac{1-\sqrt{a}}{\left(1+\sqrt{a}\right)\left(1-\sqrt{a}\right)}\right)^2\\ =\left(1+\sqrt{a}+a+\sqrt{a}\right)\left(\dfrac{1}{1+\sqrt{a}}\right)^2\\ =\left[\left(1+\sqrt{a}\right)+\sqrt{a}\left(\sqrt{a}+1\right)\right]\left(\dfrac{1}{1+\sqrt{a}}\right)^2\\ =\dfrac{\left(1+\sqrt{a}\right)\left(1+\sqrt{a}\right).1^2}{\left(1+\sqrt{a}\right)^2}=1\)