已知x,y满足方程组x方+2y=5,(1)x-y=-1 (2)(1)+(2)*2 x²+2x-3=0解得x1=1 x2=-3代入(2) y1=2 y2=-21.x1=1 y1=2时x+y分之x的三次方-xy方÷x分之x方-2x=1/(1+2)-1*2²÷(1-2*1)/1=1/3+4=4又1/32.x2=-3 y2=-2时x...