a1+a2+……+a10=140
a1+a3+……+a9=125
a2+a4+……+a10=(a1+a2+……+a10)-(a1+a3+……+a9)=15
a2+a10=a4+a8=2a6
a2+a4+……+a10
=5a6=15
a6=3
已知等差數(shù)列｛an｝的前10項(xiàng)和為140,這前10項(xiàng)中,項(xiàng)數(shù)為奇數(shù)的各項(xiàng)之和為125,求a6
已知等差數(shù)列｛an｝的前10項(xiàng)和為140,這前10項(xiàng)中,項(xiàng)數(shù)為奇數(shù)的各項(xiàng)之和為125,求a6
數(shù)學(xué)人氣：370 ℃時(shí)間：2020-05-21 05:14:29
優(yōu)質(zhì)解答
我來(lái)回答
類(lèi)似推薦
- 已知等差數(shù)列｛an｝的前10項(xiàng)和為140,這前10項(xiàng)中,項(xiàng)數(shù)為奇數(shù)的各項(xiàng)之和為125,求a6
- 等差數(shù)列{an}中,前10項(xiàng)和為140,項(xiàng)數(shù)為奇數(shù)的各項(xiàng)和為125,求S100
- 等差數(shù)列前10項(xiàng)之和為140,其中項(xiàng)數(shù)為奇數(shù)的各項(xiàng)的和為125,求其第六項(xiàng)
- 已知等差數(shù)列{an}的項(xiàng)數(shù)n為奇數(shù),且奇數(shù)項(xiàng)之和為77,偶數(shù)項(xiàng)之積為66,求中間項(xiàng)及項(xiàng)數(shù)
- 已知等差數(shù)列An的項(xiàng)數(shù)是奇數(shù),a1＝1,An的奇數(shù)項(xiàng)的和是175,偶數(shù)項(xiàng)的和是150,求這個(gè)等差數(shù)列的公差d
- 一元一次方程x2+（2m-1）x+m2=0,有兩個(gè)實(shí)數(shù)根x1,x2 （1）求實(shí)數(shù)m的取值范圍 （2）當(dāng)x12-x22=0時(shí),求m
- 城市污染對(duì)人類(lèi)有何危害
- ______ a lot of books,the boy knows much more than the boys of his age.
- Lucy often does her homework at school改為一般疑問(wèn)句
- 我父親似乎很高興.My father ___ ___ ____ happy.
- much to 和 many 區(qū)別
- You are my little little apple~誰(shuí)會(huì)翻譯吶
猜你喜歡
- 1描寫(xiě)霧海 的四字詞語(yǔ)
- 2填空1：he always gets to school by s( ).2:it is ten minutes h( ) from my home to school
- 3我國(guó)唯一注入北冰洋的河流是哪條河流
- 4就是做題時(shí)候在化學(xué)式下方量的書(shū)寫(xiě)方法.1：1的含義、
- 5將50mL4mol/L的AlCl3溶液與4mol/L的NaOH溶液反應(yīng)后得沉淀7.8g,所消耗NaOH溶液的體積為多少mL?
- 6幾個(gè)數(shù)的最大公因數(shù)是最小公倍數(shù)的（）數(shù),幾個(gè)數(shù)的最小公倍數(shù)是最大公因數(shù)的（）數(shù)
- 7需要英語(yǔ)的春節(jié)短語(yǔ)!
- 8酸根離子指什么?
- 9求解軌跡問(wèn)題
- 10設(shè)f（x）=ax^2+bx+c（a≠0） ； 若f（x+1）=f（-x）,求證-b/2a=1
- 11英語(yǔ)翻譯
- 12怎么做啊?要過(guò)程.某電視機(jī)廠(chǎng)某型號(hào)電視比去年增產(chǎn)40％,實(shí)際比計(jì)劃多生產(chǎn)20％,此型號(hào)電視今年實(shí)際產(chǎn)量是去年的（ ）％?