问题
选择题
若
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答案
A:若f(x)=x2,则lim x→0
=f(x)(x-1) x2+x lim x→0
=x2(x-1) x2+x lim x→0
=0,满足条件x(x-1) x+1
B:若f(x)=|x|,则lim x→0
=f(x)(x-1) x2+x lim x→0
=|x|(x-1) x(x+1)
,极限不存在-1,x>0 1,x<0
C:若f(x)=x,则lim x→0
=f(x)(x-1) x2+x lim x→0
=-1,存在极限x(x-1) x(x+1)
D:若f(x)=-x,则lim x→0
=f(x)(x-1) x2+x lim x→0
=1,存在极限-x(x-1) x(x+1)
故选B