f(x)dx=f(-1)(-d)=-f(-d 于是|f(x)dx=f(o)dt+(x)dx=2f(x)dx (2)因为f(x)为奇函数时即f(-x)=-f(x) 则对()[f(xu进行换元法积分得 f(x)dx=f(1dD)=f()dt于是（2）因为 , −   = −  − = − − 0 0 0 ( )d ( ) ( d ) ( )d a a a f x x f t t f t t  = a f t t 0 ( )d , −    = + = aa a a a f x x f t t f x x f x x 0 0 0 ( )d ( )d ( )d 2 ( )d . −0 (1) ( )d a 则对 中 f x x进行换元法积分得 f ( x )为奇函数时,即f ( − x ) = − f ( x ) 0 0 0 ( )d ( )( d ) ( )d a a a f x x f t t f t t − = − − =   