第1个回答 2018-01-19
(4)
f(x)
=(1/x) sinx ; x<0
=a ; x=0
=x.sin(1/x) + b ; c>0
f(0-)=lim(x->0)(1/x) sinx =1
f(0+)=lim(x->0) x.sin(1/x) + b = b
f(0) =a
=>
a=b=1
(5)
f(x)
=1/(1+e^(-x)) ; x≠0
=0 ; x=0
=lim(x->0)1/(1+e^(-x))
=1/(1+1)
=1/2
f(0) = 0
x=0 , f(x) 不连续本回答被提问者和网友采纳
f(x)
=(1/x) sinx ; x<0
=a ; x=0
=x.sin(1/x) + b ; c>0
f(0-)=lim(x->0)(1/x) sinx =1
f(0+)=lim(x->0) x.sin(1/x) + b = b
f(0) =a
=>
a=b=1
(5)
f(x)
=1/(1+e^(-x)) ; x≠0
=0 ; x=0
=lim(x->0)1/(1+e^(-x))
=1/(1+1)
=1/2
f(0) = 0
x=0 , f(x) 不连续本回答被提问者和网友采纳
第2个回答 2018-01-19
15岁初一不懂
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