極限を求めて下さい

lim_[x→−1−0] {(x^2＋1)/(x＋1)}

lim_[x→−∞] ［1/k{√(x^2＋x＋1)−√(x^2＋1)}］

lim_[x→0]［in(x^2)/{1−cos(x)}］

lim_[x→(π/2)] {cos(x)/(x−π/2)}