高数题!f(x,y)=x^3-2xy+3y^2,求f(x+y,x-y).要借题步骤

f(xy,x-y)=x^2+3xy+y^2,则f(x,y)=? 高数题!f(x,y)=x^3-2xy+3y^2,求f(x+y,x-y).要借题步骤 f(x,y)=x^2+xy+y^2-3x-6y的极值 f(x+y)=f(x)+f(y)+2xy f(xy)=f(x)+f(y),f(2)=1,f(3)=? f(xy)=f(x)+f(y)且f(8)=3则f(2)= f(xy)=f(x)+f(y),f(8)=3,则f(根2)等于 f(xy)=f(x)+f(y),f(8)=3,求f(√2), f(x)满足f(x+y)=f(x)+f(y)+2xy,(x,y属于R),f(1)=2,则f(-3)等于多少 . 对任意的实数x,y,f(x+y)=2f(y)+x^2+2xy-y^2+3x-3y,求f(x) 求函数f(x,y)=x^2-xy+y-3x的极值 f(xy,x-y)=x^2+y^2+xy;f(x,y)/∂x;f(x,y)/∂y 函数f(x)满足：对任意实数x,y都有f(x)f(y)-f(xy)/3=x+y+2,则f(36)=? 定义域在R上的函数f(x+y)满足f(x+y)=f(x)+f(y)+2xy (x,y属于R) 已知f(1)=2 求f(-3)定义域在R上的函数f(x+y)满足f(x+y)=f(x)+f(y)+2xy (x,y属于R) 已知f(1)=2 求f(-3) f(xy,x-y)=x^2-xy+y^2.求f(x,y) 对任意的x,y都有f(x+y)=2f(y)+x2+2xy-y2+3x-3y求f(x)表达式 设f(x)是定义域在(0,+∞)上的增函数,f(2)=1,且f(xy)=f(x)=f(y),求满足不等式f(x)+f(x-3)≤2的x的取值范围.f(xy)=f(x)=f(y)改为f(xy)=f(x)+f(y) 定义域在R上满足f(x+y)=f(x)+f(y)+2xy(x,y∈R),f(1)=2则f(-3)=多少