x趋向于正无穷时,ln(1+exp(x))-x的极限
问题描述：
x趋向于正无穷时,ln(1+exp(x))-x的极限
答
x=ln(exp(x))
ln(1+exp(x))-x
=ln(1+exp(x))-ln(exp(x))
=ln([1+exp(x)]/exp(x))
=ln(1+exp(-x))
取极限
=ln(1+0)
=ln1
=0