y=(x²-5x+6)/(x²+x-6)=(x-2)(x-3)/(x+3)(x-2) 定义域x≠-3 x≠2x=2是可去间断点 lim(x→2)y=-1/5x≠2时 y=(x-3)/(x+3)=(x+3-6)/(x+3)=1-6/(x+3)≠1∴y∈(-∞,-1/5)∪(-1/5,1)∪(1,+∞)
