计算 limx－>3 x的平方-9/x的平方-2x-3

题目

计算 limx－>3 x的平方-9/x的平方-2x-3

答案

(x^2-9)/(x^2-2x-3)
=(x+3)(x-3)/(x+1)(x-3)
=(x+3)/(x+1)
=1+2/(x+1)
limx－>3[1+2/(x+1)]
=1+2/(3+1)
=1+1/2=3/2