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数学 高校生

数列 この問題ってn≧2の時って途中で書かなくて良いのですか?

基本 例題129 和 S と漸化式 087 数列{an}の初項から第n項までの和Snが, 一般項anを用いて |Sn=-2a-2n+5 と表されるとき,一般項an をnで表せ。 n a=Si n≧2のときan = Sn-Sn-1 指針▷ an と Sn の関係式が与えられているから, まず 一方だけで表すために を利用する。ここでは, n=2とn=1の場合分けをしなくて済むように,漸化式 S,=-2a-2n+5でnの代わりにn+1とおいてS+1 を含む式を作り,辺々を引くこと によって S を消去する。手順をまとめると ① α=S1 を利用し,α を求める。 2 an+1=Sn+1-Sn 4³5, an, an+1 Dl£÷1F3. Sn+₁ = a₁ + a₂+...+an+an+1) CHARTD >*E* (−) Sn =a₁+a₂+ +an Sn+1−Sn= an+1 an, an+1 の漸化式から,一般項an を求める。 ( 解答 Sn=-2an-2n+5 ① とする。 ① に n=1 を代入すると S₁=−2a₁−2+5 S=α であるから a=-2a-2+5 よって ①から ②① から BASOFT したがって a=1 Sn+1=-2an+1−2(n+1)+5 Sn+1-Sn=-2(an+1−an) -2 BAL □ Sn+1 -Sn=an+1 であるから よって ht=2 3 ゆえに ここで a+2=1+2=3 数列{a,+2} は初項3,公比 1/3の等比数 FR an an+1+2= an+1=-2(an+1−a) -2 Statin 2 3 (an+2) S+n+n の等比数列であるから - =(I+ [皇學館大] pon-350X の方程式。( 基本 107,116 (+) ①での代わりにn+1 とおく。 lan+1, an だけの式。 漸化式αnt=pantg ◆特性方程式 α=12/31-1/23 題を解くと α=-2 C# (S) a FANS (1) ** 2n-1 an+2=3. (2²) ² 本 an=3. (12/3)-(12) 20(-2) 画

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英語 高校生

解答教えて頂きたいです🙇‍♂️

2 LESSON 11 (3) Choose the underlined pers ple say that Janan i Chiagur) trong 1 Choose the best answer to fill in the blanks. (81) (1) I was ( Dabout to (2) Hiroshi's undergone the medical examination already, ( Disn't he (6) ( t to ista (4) She was so stubborn that she ( Dhad him th 2 will have ) leave the room when my cell phone rang. 2 going (3) There are few places downtown for parking, ( 1 at which 2 in which 3 where 1 Can (5) The man is a responsible and capable employee Das well as 2 better than 17 3 much better than 4 superior to (7) We help one ( 1 either (8) There is ( 1 no told 4 no telling (11) If I ( (1) am (13) ( 2 doesn't he Jan Ob 1 So as 4 yet 3 soon after innen )? (9) We do not necessarily grow wiser ( 1 as 2 than (10) The World Cup is held ( 1 all 2 every ) what will happen 2 not to tell 5 not having told hasn't he hasn't ) you, ) it be true that 70% of Americans believe in angels? 2 Must 3 Does 4 May ) never change her mind. 3 would did with the extra work in the summer. 2 another 3 two tomorrow. 3 not telling 3 more than ) four years. 3 each (12) Tom didn't hear the doorbell, because he ( has been taking 3 took 4 didn't helautoqqo) ) we grow older. I would call the police immediately. 2 had been (3) were is really a problem. 4 which 2 was taking has taken ) a delightful person to work w 4 both 4 so that 4 whole temper ) a bath. ) to dense fog, most of the flights will be delayed. 2 Due 3 Because 4 would be 4 Owe (中容 (日本歯 XAC (東北学 OS THE (西南学 FUMB 10 (広島経 (注 (芝浦] (京都造 G (3

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英語 中学生

回答を解説含め教えて頂きたいです🙇‍♀️🙏

問題 9 【思考・判断・表現】 (2) 英語の授業で、 身近なものを調べて発表することになりました。 次の英文は、 ある生徒が、 チョコレート (chocolate) について調べた発表原稿です。 これを読んで、発表の最初に示す、 話の流れを表すスライドとして最も適切なものを、 右の1~4の中からつ選び、番号を答えな さい。 Hello, everyone. Do you like chocolate? I think many people do. Now, I'm going to tell you about its history. People in *ancient Mexico started to use *cacao to make chocolate. It was different from chocolate today. People drank chocolate. They thought it was good for their health. It was a kind of medicine and very expensive. YOM S How did chocolate first come to Japan? During the Edo period, people from Europe brought chocolate to Nagasaki. During the Meiji period, some people learned about making chocolate and wanted to make it in Japan. They tried very hard and finally they could. But it was still expensive. Sir tuan ob Febseit Some *confectionary companies began to make chocolate during the Taisho period. die llo freod volg DI DEST After *World War II, chocolate became sweeter and *cheaper, so it's popular now. Today you can see many kinds of chocolate in the supermarket. of og NOW DOY Which is your favorite? yobmu2 txan naritoow srt si wor *ancient Mexico = 古代メキシコ wonin tizly of price (1) confectionary companies = 7 cacao = t period World War II =*=*#**# cheaper=安い、安価な =

解決済み 回答数: 1