求导:f(x,y)=4(x-y)-x2-y2 怎么求?
求函数f(x,y)=(x2+y2)2-2(x2-y2)的极值
求函数f(x,y)=x2+xy+y2-6x-3y的极致
已知实数x,y满足1≤x2+y2≤4,求f(x,y)=x2+xy+y2的最大值和最小值
已知[(x2+y2)-(x-y)2+2y(x-y)]÷4y=1,求4x/4x2-4y2-1/2x+y的值,
已知方程x2 +y2+4x-2y-4=0,求x2 +y2的最大值
1.已知X2+Y2-4X-6Y+13=0,求Y2-X2的值
已知x2-4x+y2-6y+13=0求x2+y2的值?
圆x2+y2+2x+2y-2=0与圆x2+y2-4x-2y=0的公共弦长怎么求?
X2+Y2+8X+6Y+25=0 求代数式(x2-4y2/x2+4xy+4y2)-x/x+2y
已知X2+Y2+8X+6Y+25=0 求代数式X2++XY+4Y2分之X2-4Y2 减X+2Y分之X的值
已知x2+y2+4x-6y+13=0 求x2-2x\x2+3y2
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)的值