设f（x）是R上的奇函数,且f（x+2）=负f（x）,当x大于等于0,小于等于1时,f（x)=x,则f（7.5）等于多少

f(7.5)
=f(5.5+2)
=-f(5.5)
=-f(3.5+2)
=-[-f(3.5)]
=f(3.5)
=f(1.5+2)
=-f(1.5)
=-f(-0.5+2)
=-[-f(-0.5)]
=f(-0.5)
奇函数
=-f(0.5)
0