6x+8y=7004x+7y=500

【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 3x+2=y 5X+4=Y 7X+6=Y 9X+8=y 11x=y要如何计算 3x+2=y 5x+4=y 7x+6=y 9x+8=y 11x=y y-3x=2,y-5x=4,y-7x=6,y-9x=8,y-11x=0方程组, 3x+2=y 5x+4=y 7x+6=y 9x+8=y 11x=y 联立方程 有的话 化简下列各式,并求值:3(x-y)²-7(x-y)+8(x-y)²+6(x-y) 其中x=2,y 3(x+y)的平方-7(x+y)+8(x+y)的平方+6(x+y)-11(x+y)的平方=? 5x^3y-6x-7x^3y-8x= 2X+Y+Z=10,X+2Y+Z=-6,X+Y+2Z=8 5X+4Y-3Y=13,2X-3Y+7Z=19,3X-Y=2X 已知x.x+y.y-6x-8y+25=0,求3x.x+5y的值 已知实数x.y满足根号(x+y-8)+根号(8-x-y)=根号(3x-y-4)+根号(x-2y+7),求x,y