2x+3y=15 (x+1)/7=(y+4)/5
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)+...-(
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2x-3y+4=0则x(x*x-1)+x(5-x*x)-6y+7
x1:4x-3y=8;y=7-5x;2:2x-7y=8,3x-8y-10=0;3:4x-y=-1;4:5x-10y+15
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
例X=1 y=21.X+Y=5 X-Y=15 2.2X+3Y=4 5X+6Y=7 3.X+3Y=5 3X+Y=-1 4.
3x-2y=1 4x-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x+y+(x+y/2)=15 3x+5y+4(x+y/2)=62