y=f(x)由x^2+3y^4+x+2y=1所确定,求dy/dx

y=f(x)由x^2+3y^4+x+2y=1所确定,求dy/dx 求函数f(x,y)=x^3-3x-4y+y^2的极值, (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= f(x+y,x-y)=(x^2-y^2)/2xy,求f(x,y)! 设f(x+y,x-y)=x^2-y^2,则f(x,y)= 若f(x+y,y/x)=x^2-y^2,则F(X,Y)= 已知f(x+y,y/x)=x^2-y^2,则f(x,y)= f(x+y,y/x)=x^2-y^2求f(x,y) f(x+y,y/x)=x^2-y^2,求f(x,y),详见里面 f(x+y,x-y)=2xy(x-y),求f(x,y) 已知f(x)=3^x,求证：(1)f(x)·f(y)=f(x+y);(2)f(x)/f(y)=f(x-y). f(xy,x-y)=x^2+y^2+xy;f(x,y)/∂x;f(x,y)/∂y 由f(1)=1/4,4*f(x)*f(y)=f(x+y)+f(x-y),怎么构建出的函数f(x)=1/2cos（x*π/3）? (X,Y) f(x,y)={12y^2,0 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 设f(u)可导,函数y=y(x)由x^y+y^x=f(x^2+y^2)所确定,则dy= f(x+y)=f(x)+f(y)+2xy f(xy,x-y)=x^2+3xy+y^2,则f(x,y)=?