Y=500-5X(0

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* 已知x,y满足约束条件x-y+5>=0 x+y>=0 X 若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) 已知x.x+y.y-6x-8y+25=0,求3x.x+5y的值 Y=500-5X(0 已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 已知x^2+4y^2-4x+4y+5=0,求(y^4-x^4)/(y-2x)(x+y)*2x-y .先化简再求值：（2x+y）（2x+y)-(2x-y)平方其中X,Y满足X平方+Y平方-2X+4Y+5=0 求不等式{(x-y+5)(x+y)>=0,0 不等式组(x-y+5)(x+y)>=0 0 {2x+y/3-2y=0 2(2x+y)-5=7y