20=2*10
所以log2(20)=log2(2)+log2(10)=1+log2(10)
由f(1+x)=f(1-x)
f[log2(20)]=f[1+log2(10)]=f[1-log2(10)]
奇函数
=-f[log2(10)-1]
=-f[log2(10/2)]
=-f[log2(2*2.5)]
=-f[1+log2(2.5)]
=-f[1-log2(2.5)]
=f[log2(2.5)-1]
=f[log2(1.25)]
1
20=2*10
所以log2(20)=log2(2)+log2(10)=1+log2(10)
由f(1+x)=f(1-x)
f[log2(20)]=f[1+log2(10)]=f[1-log2(10)]
奇函数
=-f[log2(10)-1]
=-f[log2(10/2)]
=-f[log2(2*2.5)]
=-f[1+log2(2.5)]
=-f[1-log2(2.5)]
=f[log2(2.5)-1]
=f[log2(1.25)]
1