\(P=\left(\dfrac{1-a\sqrt{a}}{1-a}+\sqrt{a}\right)\left(\dfrac{1-\sqrt{a}}{1-a}\right)^2\) (ĐK: \(a\ge0;a\ne1\))
\(P=\left[\dfrac{1^3-\left(\sqrt{a}\right)^3}{\left(1-\sqrt{a}\right)\left(1+\sqrt{a}\right)}+\sqrt{a}\right]\cdot\dfrac{\left(1-\sqrt{a}\right)^2}{\left(1-a\right)^2}\)
\(P=\left[\dfrac{\left(1-\sqrt{a}\right)\left(1+\sqrt{a}+a\right)}{\left(1-\sqrt{a}\right)\left(1+\sqrt{a}\right)}+\sqrt{a}\right]\cdot\dfrac{\left(1-\sqrt{a}\right)^2}{\left(1-\sqrt{a}\right)^2\left(1+\sqrt{a}\right)^2}\)
\(P=\left[\dfrac{1+\sqrt{a}+a}{\sqrt{a}+1}+\dfrac{\sqrt{a}\left(\sqrt{a}+1\right)}{\sqrt{a}+1}\right]\cdot\dfrac{1}{\left(1+\sqrt{a}\right)^2}\)
\(P=\dfrac{1+\sqrt{a}+a+a+\sqrt{a}}{\sqrt{a}+1}\cdot\dfrac{1}{\left(1+\sqrt{a}\right)^2}\)
\(P=\dfrac{2a+2\sqrt{a}+1}{\sqrt{a}+1}\cdot\dfrac{1}{\left(\sqrt{a}+1\right)^2}\)
\(P=\dfrac{2a+2\sqrt{a}+1}{\left(\sqrt{a}+1\right)^3}\)