tolong bantuin yaaa, beserta caranya

[tex]
\left(\left(\sqrt{\frac{a}{b}}+1\right)^2+\left(\sqrt{\frac{a}{b}}-1\right)^2\right)^{-1}\\
=\left(\frac{a}{b}+2\sqrt{\frac{a}{b}}+1+\frac{a}{b}-2\sqrt{\frac{a}{b}}+1\right)^{-1}\\
=\left(\frac{2a}{b}+2\right)^{-1}\\
=\left(\frac{2a+2b}{b}\right)^{-1}\\
=\frac{b}{2a+2b}\\
=\frac{b}{2(a+b)}
[/tex]