if it exists evaluate the limit and justify each step by indicating the appropriate limit law$($s$)$ if necessary.

a$)\underset{x-2}{lim}\frac{x^3+2x^2-1}{5-3x}$

b$)\underset{x2}{lim}\frac{x^2+x-6}{x-2}$

c$)\underset{y-1}{lim}\frac{y^2-2y-3}{y^2-y-2}$

d$)\underset{x3}{lim}\frac{x-\sqrt[\phantom{2}]{2x+3}}{x-3}$