若f(x+y)=f(x)*f(y),x>0时,有0小于f(x)小于1.证f(0)=1,且x1 证f(x)在R上单调递减.

f(xy)=f(x)+f(y),证明f(x/y)=f(x)-f(y) 恒有f(x+y)=f(x)+f(y),若x>0时,f(x) y=f(f(f(x))) 求导 y=f(x), 求初等函数若f(x)f(y)=f(x+y),则f(x)= 若x∈R,f(x)满足f(x*y)=f(x)+f(y),则f(x)的奇偶性 f(x+y)=f(x)*f(y)说明什么? f(x+y)=f(x)+f(y)+2xy 若对一切实数,x.y都有f(x+y)=f(x)+f(y), 若f(x+y,y/x)=x^2-y^2,则F(X,Y)= 若函数f(x)满足f(x+y)=f(x)+f(y) (x,y∈R)证明f(-x)f(x) 若f(x)满足f(xy)= f(x) + f(y),据此能否推出f(x/y)= f(x) — f(y)? 函数f(x/y)和f(x+y)f(x/y)=f(x)/f(y),f(x+y)=f(x)+f(y)别人说是错的那f(x/y)和f(x+y)应该=什么啊? f(x+Y)+f(x-y)=2f(x)f(Y) 求其是偶函数 急 求证f（x+y）+f(x-y)=2f(x)f(y)是周期函数 已知函数f(x)=3x,求证:f(x)+f(y)=f(x+y) f(x+y)+f(x-y)=2f(x)cosy,求证f(x)为周期函数 f(x+y)=f(x)*f(y) x>0 f(x)