f(x,y)=A(x+y),0

f(x,y)=A(x+y),0 f(x+y)=f(x)+f(y),f(-3)=a,如果x>0,f(x) 设f(x)=(a^x+a^y) (a>0),证明f(x+y)+f(x-y)=2f(x)f(y)设f(x)=(a^x+a^-x) (a>0),证明f(x+y)+f(x-y)=2f(x)f(y) 已知f(x)=a^x+a^-x,g(x)=a^x-a^-x,a>0,设g(x)·g(y)=12,f(x)·f(y)=6,求f(x-y)/（x+y)的值已知f(x)=a^x+a^-x,g(x)=a^x-a^-x,a>0,设g(x)·g(y)=12,f(x)·f(y)=6,求f(x-y)/f(x+y)的值 函数f(x)=a^x (a>0,且a不等于1) 对于任意实数x y都有A.f(xy)=f(x)f(y)B.f(xy)=f(x)+f(y)C.f(x+y)=f(x)f(y)D.f(x+y)=f(x)+f(y) 函数f(x)=a的x次方,(a>0且a≠1),对于任意的实数x,y都有:A:f(xy)=f(x)f(y) B:f(xy)=f(x)+f(y) C:f(x+y)=f(x)f(y) D:f(x+y)=f(x)+f(y) 设f(x)=loga(x)（a大于0,且a不等于1）对于任意的正实数x,y都有（ ）A.f(xy)=f(x)*f(y)B.f(xy)=f(x)+f(y)c.f(x+y)=f(x)*f(y)d.f(x+y)=f(x)+f(y) 高一数学函数f(x)=a的x方(a＞0且a≠1)对于任意的实数x,y,满足的关系是A f(x+y)=f(x)f(y) B f(xy)=f(x)+f(y)C f(x+y)=f(x)+f(y) Df(xy)=f(x)f(y) 高等数学f(x+y)=f(x)+f(y)/1-f(x)f(y),求f(x)f(x+y)=f(x)+f(y)/1-f(x)f(y),则f(x)=tan(ax)怎么证明?f(x)在（-∞,+∞）上有定义,且f'(x)=a(a不等于0) (X,Y) f(x,y)={12y^2,0 已知函数f(x)满足f(ab)=f(a)+f(b),求证：f(x/y)=f(x)-f(y)(y≠0）. f(x,y)=e^-y,0 设f(x)=以a为底x的对数（a＞0,a≠1）,对于任意正实数x,yA.f(xy)=f(x)f(y)B.f(xy)=f(x)+(y)C.f(x+y)=f(x)f(y)D.f(x+y)=f(x)+f(y) 数学题f(X)对一切x y都有f(x+y)=f(x)+f(y)f(X)对一切x y都有f(x+y)=f(x)+f(y)且x>0时,f(x) F(x,y)=0 f(x+y)=f(x)*f(y) x>0 f(x) 恒有f(x+y)=f(x)+f(y),若x>0时,f(x) f(x+y)=f(x)*f(y) x>0 f(x)