lim(x->1) x^2+2x-3/x-1
lim(x–>1) (x+3)(x-1)/(x–1) = lim(x–>1) (x+3) = 1+3 = 4
lim(x–>1) (x+3)(x–1)/(x–1) = lim(x–>1) (x+3) = 1+3 = 4