f(x^2-y^2,x-y)=x+y+x^2-xy,求fy(x,y)的导数.
已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值?
已知二元函数f(xy,x+y)=x^2+y^2,求f(x,y)
f(2x+y,2y+x)=xy,求f(x,y)
对任意的实数x,y,f(x+y)=2f(y)+x^2+2xy-y^2+3x-3y,求f(x)
高数题!f(x,y)=x^3-2xy+3y^2,求f(x+y,x-y).
f(x+y,x-y)=2x②+5xy+2y②+6求f(x,y)
绝对值的导数f(x,y)=|y|cos(x)求fx(0,0)fy(0,0)
z=f(x,2x+y,xy),f有一阶连续偏导数,求dz
求二元函数f(x,y)=xy/x+y^2在点(1,1)的偏导数
如果x^2+xy+y-14,y^@+xy+x=28,求x+y的值.
f(x)具有二阶连续导数,f(0)=1,f'(0)=-1,且[xy(x+y)-f(x)y]dx+[f'(x)+x^2y]
设y=f(x^2-x),f二阶可导,求y的二阶导数