等差数列{an}中,若a6=S3=12,求an
a6=a1+5d=12
S3=a1+a2+a3=3a1+3d=12
得到d=2a1=2
所以an=a1+(n-1)d
=2n
你熟悉那些公式!
↖(^ω^)↗
猜你喜欢
- 1你和你的新同学们相处得怎么样?用英语怎么说.
- 2我的追问 2010-08-23 21:54 they __ tv in the evening they do their homework A ae watching B can't watching Cdon't wathch D do
- 31/3-2/15+3/35-4/63+5/99-6/143=?
- 45.Do you often go to ____ movies on weekends?A.read B.see C.look at
- 5Where to live —in the City or in the Country Some people like living in the city because city li
- 6设a为实数,函数f(x)=x|x-a|,讨论f(x)函数的奇偶性;
- 7英语短文 在公共场所吸烟的危害
- 8滴定时待测液为什么只能装在滴定管里不能装在锥形瓶里?
- 9(sinx)2次方和(cosx)2次方的n阶导数怎么求?
- 10许多中国人现在在学习英语 用英语怎么说