1.计算：x-y分之x+y + y-3分之2x=(x+y)/(x-y)+2x/(y-3)=((x+y)(y-3)+2x(x-y))/(x-y)(y-3)=(xy-3x+y^2-3y+2x^2-2xy)/(x-y)(y-3)=(-3x+y^2-3y+2x^2-xy)/(x-y)(y-3)=(-3x-3y+y^2-xy+2x^2)/(x-y)(y-3)2.计算：x+3分之x&#...