lim=(x²-y²-2x+2y)/(x+ y-2) ① （x,y)→（2,0） ②（x,y)→（0,2）极_数学解答

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：365 ℃　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