若y=1−4x+4x−1+4
若2x-3y+4=0则x(x*x-1)+x(5-x*x)-6y+7
若实数x,y满足x≥1x+y≤4x−2y+c≤0
若x=-1/4,能否确定代数式(2x-y)(2x+y)+(2x-y)(y-4x)+2y(y-3x)的值?
若|x+2y-1|+y²+4y+4=0,求(2x-y)²-2(2x-y)(x+2y)+(x+2y)&
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
{3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1
{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
设z=2x+y,变量x,y满足条件x−4y≤−33x+5y≤25x≥1
若集合A={(x,y)|y=1+4−x
已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(
已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y