pooh031 寫到:設f(x)為一函數且滿足 f(x+5)=f(x)、f(-x)=x、f(1)=365、求f(-911)?
答案寫 f(1)=f(1+5)=f(1+5*2)=f(1+5*3).....=f(1+5*182)=f(911)
看不太懂為什麼 f(1+5)=f(1+5*2)=f(1)??
此題的條件互相矛盾:
f(-x) = x, ==> f(-5/2) = 5/2, f(5/2) = -5/2
If x = -5/2, then by f(x+5)=f(x) ==> f(5/2) = f(-5/2)