{x+y=840;4x+8x+8y=4y+9y+9x
9y=3x-(x-1),4(x+y)-(2x+4)=8y
{4/(x+y)+6/(x-y)=3 {9/(x-y)-1/(x+y)=1
已知4x=9y求(1)x+y/y (2)y-x/2x
[(x+2y)(x-2y)-(x-2y)^2+8y(x+y)]除以4x=
化简(x+y)+(2x+1/2y)+(3x+2/3y)+(4x+3/4y)+...+(9x+8/9y)=?
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
(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai
9y=3x-(x-1),4(x+y)-(x+4)=8y解方程组
x(y+2)+(4-x)=9与x(y+3)+y(8-x)=14解方程式