lim=(x²-y²-2x+2y)/(x+ y-2) ① （x,y)→（2,0） ②（x,y)→（0,2） 极限怎么求
人气：425 ℃ 时间：2020-04-16 05:27:39
解答
lim(x,y)→(2,0) (x²-y²-2x+2y) / (x+y-2)= lim (x²+xy-2x -xy-y²+2y) / (x+y-2)= lim [x(x+y-2)-y(x+y-2)] / (x+y-2)= lim [(x-y)(x+y-2)] / (x+y-2)= lim (x-y)= 2 - 0= 2
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