x + y = 95（0.4*x + 0.78*y）/95 = 0.6

（x+y-5)*（x+y-5)+（x-y+3)=0 x*x-y*y 已知:3x-5y=0,求x/y,x-y/y,x-y/x X+x+x+y+y=95 x+x+y+y+y=105 x,y分别为多少 求y=(x^2)+2x(x≥0) y=-x+2x(x x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 x>=0,y x*x+2x+y*y-4y+5=0 x= y= 已知x>0,Y>0,如何证x^2/y+y^2/x>=x+y 变量x,y满足x-2y=0,x (x+y)(x+y-10)+25=0,且x-y=3,求x,y (x+y)(x+y-10)+25=0,且x-y=3,求x,y 设Z=X+Y,其中X,Y满足X+2Y>=0,X-Y （5x-6y)(x+y)=0(x不等于y),则y/x= 已知|3x-y|+|x+y|=0,求x-y除以x*y的值. 化简 x / y(x+y) - y / x(x+y) = Y=X^2X (X>0) 求导Y=X^2X (X>0) 求d(Y)/d(X) y=x(x 求y=x^x^x(x>0)的导数