对所有实数x、y,若函数y=f(x)满足f(xy)=f(x)f(y),且f(0)≠0,则f(2009)=(  ) A.2008 B.2009 C.1 D.2

问题描述:

对所有实数x、y,若函数y=f(x)满足f(xy)=f(x)f(y),且f(0)≠0,则f(2009)=(  )
A. 2008
B. 2009
C. 1
D. 2

因为f(xy)=f(x)f(y),
故f(0)=f(0)f(0);
又∵f(0)≠0,
∴f(0)=1,
∴f(0)=f(2009×0)=f(2009)f(0)=f(2009)=1,
故本题选C.