几道一元二次的方程7X-2Y=39X+2Y=-19 5X-6Y=97X-4Y=-5 3X+5Y=212X-5Y=-11
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
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
若关于x,y的一元二次方程组5x+2y=4+3a,2x+5y=3+a.的解满足x+y
解一元二次方程组.(x+y)/2+(x-y)/3=6 4(x+y)-5(x-y)=2
6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5
方程2分之x+y+2分之x-y=7,4(x+y)-5(x-y)=2
解方程x+y+(x+y/2)=15 3x+5y+4(x+y/2)=62
解方程组(x+y)(x-2y)=-5 (x-y)(x+2y)=7
化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1
已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(
数学题……555{(3x+y)(3x-y)-(x-5y)(5x-y)-(x-2y)²÷(-4x),x=-2.y