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lim(xy)/根号下(xy+1)-1=?注(x,y)--(0,0)
人气:337 ℃ 时间:2020-03-29 04:33:41
解答
(x,y) ->(0,0) => u = xy ->0
lim (x,y) ->(0,0) xy / [√(xy+1) - 1]
= lim u ->0 u / [√(u+1) - 1]
= lim u ->0 u *[√(u+1) + 1] / u
= lim u ->0 [√(u+1) + 1]
= 2
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