3(x-5)-8y=-x-(-0.5y)=7,求x,y的值

已知x.x+y.y-6x-8y+25=0,求3x.x+5y的值 已知：x-y=1,x+y=-7,求代数式3（x+y)+20(x-y)-5的值 已知x-2y=2016,求[(3x+2y)(3x-2y)-(x+2y)(5x-2y)]除以8x的值 已知x-2y=2012,求[(3x+2y)(3x-2y)-(x+2y)(5x-2y)]÷8x的值 已知|3x-y|+|x+y|=0,求x-y除以x*y的值. 求代数式3x²y+5x-0.5x²y+3.5x²y-2的值,其中x=1/5,y=7 若x-y/x+y=5,求x-y/2x+2y+5x+5y/3x-3y的值 已知x+y=-5,x*x+y*y=19求xy和（x-y)*(x-y)的值 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知x-y=3,求代数式7-x+y-(y-x)的平方的值 若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值 若x+y=-5,xy=3,求x/y+y/x的值