Evaluate each limit$.$ If the limit does not exist, say so$.$ If the limit value is infinite, indicate whether it is $$ or $-.$ Follow the processes introduced in class.

a$.\underset{x}{lim}\frac{x^{2}2}{x^3-1}$

b$.\underset{x}{lim}\frac{(2x5{)}^7}{3x^7}$

c$.\underset{x}{lim}(\frac{3x^3}{x^3}-\frac{5x^2}{2x^2}\frac{x}{2x}4)$