由y=x2-2x+3y=x+3，解得x=0y=3或x=3

已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 由二元一次方程组3X+2Y=9,2X+3Y=6,则得X+Y= ,X-Y=?. 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y 已知X 、Y为实数,Y=根下{（X2-4）+根下（4-X2）+1}除以x-2,求3X+4Y得值 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 已知实数x,y满足4x+3y大于或等于0,则u=x2+y2+4x-2y最小值是 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5