设f(x)是(-无穷,+无穷)上的奇数,f(x+2)=-f(x),当0<=x<=1时,f(x)=x,则f(7.5)=?
f(0.5)=0.5
f(7.5)=-f(5.5)=f(3.5)=-f(0.5)=-0.5