已知函数f(x)满足f(x+y)+f(x-y)=2f(x)f(y),x和y都属于R,且f(0)≠0,试证明f(x)是偶函数

已知函数f(x)对于任意实数xy 满足f(x+y)=f(x)+f(y).求证f(x-y)=f(x)-f(y) 已知函数f(x)满足f(x+y)+f(x-y)=2f(x)×f（y）,且f(0)≠0,证明f(x)是偶函数 已知函数y=f(X)满足f(x)=2f(1/x)+x,求f(x)的表达式 已知函数y=f(x)满足3f(x)+f(-x)=5x,则f(x)= 已知二次函数y=f(x)满足f(x+1)=f(x)+x+1,求f(x) 已知函数f(x)满足：f(1)=1/4,4f(x)f(y)=f(x+y)+f(x-y),则f(2015)= 已知函数f(x)满足:f(1)=1/4,4f(x)f(y)=f(x+y)+f(x-y).则f(2010) 已知函数f(x)满足,f(1)=0.25,4f(x)f(y)=f(x+y)+f(x-y) 则f（2010）= 已知函数f(x)满足f(2)=1/2,2f(x)f(y)=f(x+y)+f(x-y),则f(2012)=? 已知函数f(x)满足f(1)=1/4,f(x)+f(y)=4f(x+y/2)*f(x-y/2)则f(-2011)=? 已知函数f(x)满足f(3)=1/3,3f(x)f(y)=f(x+y)+f(x-y),求f(1812) 已知函数f(x)满足:f(1)=0,f(x)f(y)=f(x+y)+f(x-y),则f(2014)= 高中数学函数题已知函数f(x)满足：f(1)=1/4,4f(x)f(y)=f(x+y)+f(x-y) (x,y属于R),则f(2010)=?已知函数f(x)满足：f(1)=1/4,4f(x)f(y)=f(x+y)+f(x-y) (x,y属于R),则f(2010)=? 已知函数y=f(x)满足f(-2)>f(-1),f(-1) 已知函数f(x)满足f(x)+3f(-x)＝3x,求f(x) 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）. 已知函数f(x)满足:f(1)=1/4,4f(x)f(y)=f(x+y)+f(x-y).则f(2010)=?(x,y属于R）为什么f(x+3)=-f(x+6) 已知一次函数f(x)满足f[f(x)]=4x+3,求f(x)