Answer: See below
Step-by-step explanation:
[tex]\begin{array}{l}\frac{\sqrt{a+1}-2}{\sqrt{a+1}+2}\\\\=\frac{(\sqrt{a+1}-2)(\sqrt{a+1}-2)}{(\sqrt{a+1}+2)(\sqrt{a+1}-2)}\\\\=\ \frac{(\sqrt{a+1}-2)^2}{(\sqrt{a+1})^2-2^2}\\\\=\frac{(\sqrt{a+1}-2)^2}{a-3}\end{array}[/tex]
