x>=0,y
x>=0,y
设Z=X+Y,其中X,Y满足X+2Y>=0,X-Y
x*y'*sin(y/x)-y*sin(y/x)+x=0 求微分方程的解
已知|3x-y|+|x+y|=0,求x-y除以x*y的值.
(x+y)y'+(x-y)=0的通解
已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值?
y=x^x(x>0)求导
x>1,y>0,且满足xy=x^y,x/y=x^3y,求x+y
已知x*x+4x+y*y-2y+5=0,则x*x+y*y=?
设x>1,y>0,若x^y+x^-y=2根号2,则x^y-x^-y等于
变量x,y满足x-2y=0,x
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*