x趋于0+与x趋于0-分别怎么求极限啊?
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发布时间:2023-10-12 07:21
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时间:2024-11-15 21:46
x→0+,即x = 0 + ε,x = ε
x→0-,即x + ε = 0,x = - ε
ε是一个趋向0的数值
例如求lim(x→0) e^(1/x)
当x→0+时,令x = ε
即lim(x→0+) e^(1/x) = lim(ε→0) e^(1/ε) = e^∞ = +∞
当x→0-时,令x = - ε
即lim(x→0-) e^(1/x) = lim(ε→0) e^(1/(- ε)) = lim(ε→0) e^(- 1/ε)
= lim(ε→0) 1/e^(1/ε) = 1/e^∞ = 0