定義在R上的函數(shù)f(x)與g(x),對任意x都有f(x)+f(-x)=0與g(x)=g(x+4)成立.已知f(-2)=g(-2)=6,且f(f(2)+g(2))+g(f(-2)+g(-2))=-2+2g(4),則g(0)=( )
A.2
B.1
C.0
D.-1
【答案】分析:由條件知f(x)是奇函數(shù),g(x)是周期為4的函數(shù),又f(-2)=g(-2)=6,可求得f(2)+g(2)=0,繼而可求得f[f(2)+g(2)]=0,g(f(-2)+g(-2))=g(0),再利用f(f(2)+g(2))+g(f(-2)+g(-2))=-2+2g(4),可求得g(0)的值.
解答:解:由條件知f(x)是奇函數(shù),g(x)是周期為4的函數(shù).
∵f(-2)=g(-2)=6,
∴f(2)=-6,g(-2)=g(4-2)=g(2)=6,
∴f(2)+g(2)=-6+6=0,
∴f(f(2)+g(2))=f(0)=0,
g(f(-2)+g(-2))=g(12)=g(0),
∵g(4)=g(0),
于是原式變?yōu)間(0)=-2+2g(0),
∴g(0)=2,
故選擇A.
點(diǎn)評:本題考查函數(shù)的周期性,著重考查函數(shù)的奇偶性與周期性的綜合應(yīng)用,求得f[f(2)+g(2)]=0,g(f(-2)+g(-2))=g(0)是關(guān)鍵,屬于中檔題.