已知函数f(x)是定义在实数集R上的不恒为零的偶函数,且对任意实数X都有Xf(X+1)=(1+X)f（X）则f（2.5）的值

令 x = 1.5 得：1.5f(2.5) =2.5f(1.5)所以f(2.5)= 5f(1.5)/3令x = 0.5得：0.5f(1.5)=1.5f(0.5)所以f(1.5) = 3f(0.5)令x = -0.5得：-0.5f(0.5) = 0.5f(-0.5)所以f(0.5) = -f(-0.5)因为f(x)是偶函数所以f(0.5) = f(-0....