EValuate the following limits$.$

a$)\underset{x0}{lim}100$

Answer

b$)\underset{x-1}{lim}{x}^2+x+1$

Answer :

c$)\underset{x-1}{lim}\frac{x-1}{x+1}$

d$)\underset{x3}{lim}\frac{x^3-27}{x-3}$