# Calculus: General Differentiation – #23

Question: Evaluate the following limits if they exist. If a limit does not exist, explain why.

a) $\underset{a\to 1}{\mathop{\lim }}\,\frac{{{a}^{2}}+6a-7}{a-1}$

b) $\underset{x\to 0}{\mathop{\lim }}\,\frac{\cos x}{x}$

c) $\underset{x\to {{0}^{+}}}{\mathop{\lim }}\,\ln x$