题目3.(10题11分分)-|||-问∞是否为下列函数的孤立奇点?如果是,指出其奇点类型.-|||-(1).cos 2;-|||-(2) ((1+2z))^2;-|||-(3) dfrac (1)({e)^2-1};-|||-(4) sin dfrac (1)(z)题目解答答案