
高数 求极限 大佬快来
3个回答
2017-10-06
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lim_(x->0) sin2x/tan3x=lim_(x->0) (2x)/(3x)=2/3
lim_(x->π/2) cosx/(2x-π)
=lim_(x->π/2) sin(π/2-x)/(2x-π)
=-1/2 lim_(x->π/2) sin(π/2-x)/(π/2-x)
let t=π/2-x
lim_(x->π/2) cosx/(2x-π)
=-1/2 lim_(t->0) sint/t
=-1/2
lim_(x->π/2) cosx/(2x-π)
=lim_(x->π/2) sin(π/2-x)/(2x-π)
=-1/2 lim_(x->π/2) sin(π/2-x)/(π/2-x)
let t=π/2-x
lim_(x->π/2) cosx/(2x-π)
=-1/2 lim_(t->0) sint/t
=-1/2
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谢谢
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