题目没有错
f(-x)=f(x), => 函数为偶函数
f(x)=-f(x+1)=f(x+2)=-f(x+3)
f(7/2)=f(-1/2+2+2)=f(-1/2)=f(1/2)
f(7/3)=f(1/3+2)=f(1/3)
f(7/5)=f(-3/5+2)=f(-3/5)=f(3/5)
且在[0,1]上单调递减
所以f(3/5)