f(x)是定义在R上的偶函数,满足f(x+2)=-f(x),当x∈[0,1]时,f(x)=x,则f(5.5)=

f(5.5)
=f(3.5+2)
=-f(3.5)
=-f(1.5+2)
=f(1.5)
=f(-0.5+2)
=-f(-0.5)
f(x)是偶函数则f(x)=f(-x)
-f(-0.5)=-f(0.5)
当x∈[0,1]时,f(x)=x
所以f(0.5)=0.5
f(5.5)=-f(0.5)=-0.5