ĐK: \(\left\{{}\begin{matrix}a\ge0\\a\ne1\end{matrix}\right.\)
\(C=\left[\frac{\left(1-\sqrt{a}\right)\left(1+\sqrt{a}+a\right)}{1-\sqrt{a}}+\sqrt{a}\right].\left[\frac{1-\sqrt{a}}{\left(1-\sqrt{a}\right)\left(1+\sqrt{a}\right)}\right]^2\)
\(=\left(1+\sqrt{a}+a+\sqrt{a}\right).\frac{1}{\left(1+\sqrt{a}\right)^2}\)\(=\left(1+2\sqrt{a}+a\right).\frac{1}{\left(1+\sqrt{a}\right)^2}\)
\(=\left(1+\sqrt{a}\right)^2.\frac{1}{\left(1+\sqrt{a}\right)^2}=1\)