1、奇函數(shù)乘以奇函數(shù)等于偶函數(shù)。奇函數(shù)乘偶函數(shù)是奇函數(shù)，奇函數(shù)加減奇函數(shù)是奇函數(shù)，偶函數(shù)加減偶函數(shù)是偶函數(shù)，奇函數(shù)乘奇函數(shù)是偶函數(shù)，偶函數(shù)乘偶函數(shù)是偶函數(shù)。偶函數(shù)乘偶函數(shù)是偶函數(shù)。
2、函數(shù)的奇偶性也就是對(duì)任意xEl，若f（-x）=f（x），即在關(guān)于y軸的對(duì)稱點(diǎn)的函數(shù)值相等，則f（x）稱為偶函數(shù)；若f（-x）= - f（x），即對(duì)稱點(diǎn)的函數(shù)值正負(fù)相反，則f（x）稱為奇函數(shù)。在平面直角坐標(biāo)系中，偶函數(shù)的圖象對(duì)稱于y軸，奇函數(shù)的圖象對(duì)稱于原點(diǎn)?？蓪?dǎo)的奇（偶）函數(shù)的導(dǎo)函數(shù)的奇偶性與原來函數(shù)相反。定義在對(duì)稱區(qū)間（或點(diǎn)集）上的任何函數(shù)f（x）都可以表示成奇函數(shù)φ（x）和偶函數(shù)ψ（x）之和。
