17 設 f (x)在-L < x <L的傅立葉級數(Fourier series)為,下列敘述何者正確?(A) f (x)為偶函數(even function),a0 = 0(B) f (x)為奇函數(odd function),= 0(C)A=(D)f (x)為奇函數,級數在x = L的左極限(left-hand limit)收斂到零