1)(a²-b²)/(a+b)=(a+b)(a-b)/(a+b)=a-b2)-a³/a^4=-1/a3)(xy-x-y+1)/(y²-2y+1)=【（xy-x)-(y-1)】/(y-1)²=【x（y-1）-(y-1)】/(y-1)²=【（x-1）（y-1）】/(y-1)²=(x-1)/(y-1) 望...