若x=2012,y=2013,则(x+y)×[(x^2+y^2)/x^4-y^4)]
[x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013
已知x*x+4x+y*y-2y+5=0,则x*x+y*y=?
若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*
若3x-4y=0,则x/y=______,(x-y)/y=______,(3x+2y)/(2x+3y)=_____.
若5x+3y=3x+4y=x+2y+6,则x+y=___
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于
x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20
{(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6
已知4x=9y求(1)x+y/y (2)y-x/2x