lim(an^2/(3n+1)-n)=b a+b=?_数学解答

lim(an^2/(3n+1)-n)=b a+b=?

人气：318 ℃　时间：2020-04-13 09:59:57

解答

你好!
lim [an²/(3n+1) - n]
= lim [an² - n(3n+1)]/(3n+1)
= lim [(a-3)n² - n] / (3n+1)
极限存在,必有a-3=0即a=3
极限为-1/3 即 b = -1/3
故 a+b = 8/3