Evaluate the following :

$\underset{x\to 0}{\lim }\frac{a^x-a^{-x}}{x}$

Evaluate the following :

$\underset{x\to 1}{\lim }\frac{3^x-3}{x-1}$

Evaluate the following :

$\underset{x\to 0}{\lim }\frac{3^x-2^x}{4^x-3^x}$

Evaluate the following :

$\underset{x\to 1}{\lim }\frac{2^{x-1}-1}{\sqrt{x}-1}$.

Evaluate the following:

$\underset{x\to 0}{\lim }\frac{\sqrt{3-2x}-\sqrt{3}}{x}$

Evaluate the following:

$\underset{x\to 5}{\lim }\frac{\sqrt{x-1}-2}{x-5}$