定义域在R上的函数满足f(x+y)+f(x-y)=2f(x)f(y) f(0)≠0 f(1/2)=0 求证f(x)为偶函

定义域在R上的函数满足f(x+y)+f(x-y)=2f(x)f(y) f(0)≠0 f(1/2)=0 求证f(x)为偶函 定义域在R上的函数满足f(x+y)+f(x-y)=2f(x)f(y) f(0)≠0 f(1/2)=0 求:f(x)为偶函 函数f（x）满足f（x+y）+f（x-y）=2f（x）·f（y）,其定义域为R,求证f（x）为偶函数（f（x）≠0）. 定义域在R上的增函数y=f(x)对任意x,y∈R都有f(x+y)=f(x)+f(y) (1)求f(0) (2)求证：f( 若定义域为R函数f(x)满足f(x+y)=2*f(x)*f(y),且f(0)不等于0,证明f（x）是偶函数 定义域在R上的函数f(x)满足f(x+y)=f(x)+f(y)+2xy,f(1)=2,则f(-3)=? f(x) 在定义域（0,正无穷）上是增函数,满足f(2)=1,f(xy)=f(x)+f(y).求不等式f(x)+f(x- 已知函数f(x)满足f(x+y)+f(x-y)=2f(x)f(y)(x∈R,y∈R),且f(0)≠1. 已知f(x)在定义域x>0上为增函数,满足f(xy)=f(x)+f(y),且f(2)=1 定义在R上的函数f(x)满足f(x+y)+f(x-y)=2f(x)f(y)且f(1/2)=0 f(0)≠0 设定义域为R的函数f(x),对任意实数X,Y满足f(x+Y)=f(x)*f(y),且f(0)≠0求证f(x)>0 定义在R上的函数f(x)满足f (x + y) = f (x) + f ( y )(x,y∈R),当x>0时,f (x)