1.阅读材料,回答问题:
化简$\frac{1}{\sqrt{2}+1}$:$\frac{1}{\sqrt{2}+1}$=$\frac{1×(\sqrt{2}+1)}{(\sqrt{2}+1)(\sqrt{2}-1)}$=$\frac{\sqrt{2}-1}{(\sqrt{2})^{2}-1}$=$\sqrt{2}$-1;
化简:$\frac{2}{3-\sqrt{5}}$:$\frac{2}{3-\sqrt{5}}$=$\frac{2(3+\sqrt{5})}{(3-\sqrt{5})(3+\sqrt{5})}$=$\frac{2(3+\sqrt{5})}{{3}^{2}-(\sqrt{5})^{2}}$=$\frac{2(3+\sqrt{5})}{4}$=$\frac{3+\sqrt{5}}{2}$.
(1)以上化简过程运用了哪个乘法公式?
(2)依照上述化简方法化简$\frac{2}{\sqrt{5}+\sqrt{3}}$;
(3)计算:$\frac{1}{\sqrt{2}+1}$+$\frac{1}{\sqrt{3}+\sqrt{2}}$+$\frac{1}{\sqrt{4}+\sqrt{3}}$+…+$\frac{1}{\sqrt{100}+\sqrt{99}}$的值.