f(x)=是R上的奇函数f(x+2）=-f(x),
f(47.5)=f(45.5+2)=-f(45.5)
f(45.5)=-f(43.5) f(47.5)=f(43.5)
f(43.5)=-f(41.5)
f(41.5) =-f(39.5) f(47.5)=f(39.5)
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f(47.5)=f(3.5)
f(3.5) =-f(1.5)
f(1.5)=-f(-0.5) f(47.5)=f(-0.5)=-f(0.5)
0≤x≤1时f(x)=2x+1 x=0.5 f(0.5)=2
f(47.5)=f(-0.5)=-f(0.5)=-2
f(47.5)的值为-2