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请问lim(x→1) (3x+5)/(x^3-1) 怎样求?
人气:408 ℃ 时间:2020-04-02 22:23:21
解答
(3x+5)/(x^3-1)=(3X+5)/(X-1)(X^2+X+1)
=3(X-1)/(X-1)(X^2+X+1)+8/(X^3-1)
=3/[(X^2+X+1/4)+2/4]+8/(X^3-1)
=3/[(X+1/2)^2+3/4] + 8/(X^3-1)
令X=1,则原式=1+∞=∞
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