NAN DA XUE JING PIN KE CHENG 定义2.设f(x)在(-0,-M(M,+∞)内有定义 若∨E>0,3X>0,当x>时,相应的函 数值满足 f(rake 则称a为f(x)当x->∞时的极限,记作 imf(x)=a或∫(x)→>a,(x→>∞) 由定义1,2可知 lim f (x=a e lim f (x)=lim f(x=a x→00 OD 高等數粤定义2. 设f (x)在(−, −M) (M, +)内有定义. 若  >0, X >0, 当|x|>X时, 相应的函 数值满足 | f (x) −a |<  则称a为 f (x)当x→时的极限, lim ( ) = ( ) → ,( → ) → f x a f x a x x 或 由定义1, 2可知 f x a f x f x a x x x =  = = → →+ →− lim ( ) lim ( ) lim ( ) 记作