ĐKXĐ:...
\(A=\left(\frac{\sqrt{a}+1}{\sqrt{a}\left(\sqrt{a}-1\right)\left(\sqrt{a}+1\right)}+\frac{a}{\sqrt{a}\left(\sqrt{a}-1\right)\left(\sqrt{a}+1\right)}\right):\left(\frac{\left(\sqrt{a}-1\right)\left(a+\sqrt{a}+1\right)}{\sqrt{a}\left(\sqrt{a}-1\right)^2}\right)\)
\(=\frac{\left(a+\sqrt{a}+1\right)}{\sqrt{a}\left(\sqrt{a}-1\right)\left(\sqrt{a}+1\right)}.\frac{\sqrt{a}\left(\sqrt{a}-1\right)^2}{\left(\sqrt{a}-1\right)\left(a+\sqrt{a}+1\right)}=\frac{\sqrt{a}-1}{\sqrt{a}+1}\)