lim=(x²-y²-2x+2y)/(x+ y-2) ① (x,y)→(2,0) ②(x,y)→(0,2) 极限怎么求

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lim=(x²-y²-2x+2y)/(x+y-2)①(x,y)→(2,0)②(x,y)→(0,2)极限怎么求lim=(x²-y²-2x+2y)/(x+y-2)①

lim=(x²-y²-2x+2y)/(x+ y-2) ① (x,y)→(2,0) ②(x,y)→(0,2) 极限怎么求
lim=(x²-y²-2x+2y)/(x+ y-2) ① (x,y)→(2,0) ②(x,y)→(0,2) 极限怎么求

lim=(x²-y²-2x+2y)/(x+ y-2) ① (x,y)→(2,0) ②(x,y)→(0,2) 极限怎么求
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