數(shù)列總和S=10+12=22
則有12-10=2為其中間項(xiàng)
數(shù)列和S=n*中間項(xiàng)
故n=11...
解畢...
一個(gè)等差數(shù)列有奇數(shù)項(xiàng),它的奇數(shù)項(xiàng)和為12,偶數(shù)項(xiàng)的和為10,求它的項(xiàng)數(shù)?
一個(gè)等差數(shù)列有奇數(shù)項(xiàng),它的奇數(shù)項(xiàng)和為12,偶數(shù)項(xiàng)的和為10,求它的項(xiàng)數(shù)?
數(shù)學(xué)人氣:248 ℃時(shí)間:2020-02-06 14:25:50
優(yōu)質(zhì)解答
我來回答
類似推薦
- 項(xiàng)數(shù)為偶數(shù)的等差數(shù)列,其奇數(shù)項(xiàng)的和為12,偶數(shù)項(xiàng)的和為28,且末項(xiàng)比首項(xiàng)大30,則此數(shù)列的項(xiàng)數(shù)為?
- 有一列項(xiàng)數(shù)為奇數(shù)的等差數(shù)列,其中奇數(shù)項(xiàng)之和為44,偶數(shù)項(xiàng)之和為33,則項(xiàng)數(shù)為_,中間項(xiàng)為_.
- 項(xiàng)數(shù)為奇數(shù)的等差數(shù)列,奇數(shù)項(xiàng)之和為44,偶數(shù)項(xiàng)之和為33,求這個(gè)數(shù)列的中間項(xiàng)及項(xiàng)數(shù).
- 一個(gè)項(xiàng)數(shù)為偶數(shù)的等差數(shù)列,奇數(shù)項(xiàng)的和與偶數(shù)項(xiàng)的和分別為24和30.若最后一項(xiàng)比第一項(xiàng)多10.5,則該數(shù)列的項(xiàng)數(shù)為( ?。?A.18 B.12 C.10 D.8
- 含2n+1個(gè)項(xiàng)的等差數(shù)列,其奇數(shù)項(xiàng)的和與偶數(shù)項(xiàng)的和之比為( ?。?A.2n+1n B.n+1n C.n?1n D.n+12n
- 若x/y=2/7則7x²-3xy+2y²/2x²-3xy+7y²=
- x的平方+2 y平方-2xy+8y+16=0,則x-y等于
- 只見樹木不見森林?
- I can play basketball( )(good)
- she can's see anything in the dark room 改為同義句
- 李賀的馬詩(shī)前兩句通過對(duì) 什么 一帶景物的描寫
- 平面與平面的夾角,取值范圍是多少?
猜你喜歡
- 1y是x的函數(shù),用什么表示什么
- 24.She can`t find her mother.Can you help ______.
- 3比喻句判斷:1.雄偉的長(zhǎng)城仿佛一條巨龍 2.平靜的湖面像明亮的鏡子 3.我好像在哪里見過你.
- 4王昌齡詩(shī)
- 5“不管是大還是小”用英語說是不是No matter great or little?
- 6甲 乙 丙 丁四位同學(xué)依序循環(huán)報(bào)數(shù)規(guī)定,①甲 乙 丙 丁首次報(bào)數(shù)依次為1 2 3 4,接著甲報(bào)5,乙報(bào)6…………按此規(guī)律,一直報(bào)下去.②當(dāng)數(shù)報(bào)道50時(shí),若報(bào)出的數(shù)為3的倍數(shù),舉一次收.擇甲要舉幾次收?
- 7茶葉中氨基酸含量與什么有關(guān),為什么北方的氨基酸含量高,南方的茶多酚含量高
- 8△ABC中,∠B=∠C,D為BC上一點(diǎn),AB上取BF=CD,AC上取CE=BD,則∠FDE等于( ?。?A.90°-∠A B.90°-12∠A C.180°-∠A D.45°-12∠A
- 9f(x)=1/3x^3-ax^2+(a^2-1)x,若方程f(x)=0有三個(gè)實(shí)數(shù)根,求a的取值范圍
- 10It's business,not personal.漢語意思是什么?
- 11Staying at home
- 12電路中的短路和短接所表達(dá)的意思一樣嗎,都是用電器不能使用,