In all these problems, write I if the limit is either $+\infty$ or $-\infty$.

Find the following limits:

(a) $\lim_{x \rightarrow 1} \frac{x^4 - 3x^3 + x^2 - x +2}{x^3 - 2x + 1} =$
.

(b) $\lim_{x \rightarrow 0} \frac{\cos(x) - 1}{x^2} =$
.

(c) $\lim_{x \rightarrow 0} \frac{e^x - 2^x}x =$
.