2x-y=7 2x+3y=1 3x+5y21 5y-3y=1用代数消元法怎么解?
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
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-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(
x+y=3 x+2y=9 3/x+1=y y-x=3 y=2x-3 y-3x=1 2(x+1)-y=6 7x-5y=-9
7x-3y/5=5x-y/3-x+y/2 x-1/5=y+1/3
解方程组{(x-2)(y+3)=(x+1)(y-1) {(x+1)(y+1)=(x-1)(y+5)
{ x-y/7-x+y/10=1/2 {2(x-y)+5(x+y)=3
(2x+y-1)(2x-y+1)-(3x+y)(3x-y),其中x=5分之1,
用代数法解下列方程组:(1)2x+3y=1 (2)7x+6y=2
1.已知二元一次5分之x-9y=3分之1y+2,用含有x的代数表示y的形式为
(3x-y)^2+(3x+y)(3x-y),x=1,y=-2