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数学 高校生

この問題の④がn=1の時も成り立つとありますが、どこで成り立っているのかが分かりません!誰か解説してくださるとありがたいです、よろしくお願いいたします🙇

B1-40 (58) 第1章 数 列 Think ○見るたり多度 例題 B1.27 いろいろな数列の和 ( 2 ) Sm=1−22+32-4'++ (−1)" を求めよ. 解答) その和を分けて考える必要がある. nが偶数、つまり=2mmは自然数のとき、 wwwwwww wwwwwwwwwwwwwww Sam=1-2+3-4++ (2m-1)-(2m)2 2m III Colu nが奇数、つまり=2m+1のとき =(12−22)+(32-4°)+…+{(2m-1)-(2m)2} 第 m項 S2m+1=1-2°+32-4°++ (2m-1)-(2m)+(2m+1)2 =(12-2)+(3°-4°)+…+{(2m-1)-(2m)2}+(2m+1)2 nが偶数のとき, n=2mmは自然数) とおくと, wwwwwwwwwwwwwww. Sm=S2m=(12−22)+(3-4)+…+{(2m-1)-(2m)2} ={(k-1)-(2k)}=2(-4k+1) k=1 第 (2m+1)項 いう m 第3項 こ①初う例 n=2,4,6 数列 {(2m-1)^- 初項から第 =-4mm(m+1)+m=-m(2m+1) n=2mより,m=in を①に代入して, == S,=-1/2"(n+1) ② __(n+1) での和と考える 和はnで表す っちの方 ○かりやよい wwwwwwwwwww nが奇数のとき,n=2m+1(mは自然数) とおくと, Sw=Szm+1= (12-2) + (3-4) +...・・・ +{(2m+1)-(2m)2}+(2m+1)^ =Szm+(2m+1)=-m(2m+1)+(2m+1)2 (m+1)(2m+1) (3 n=2m+1より,m= (n-1) を③ に代入して, S.=2+1/2)(n-1+1)=1/2m(n+1)……③ ④は n=1のときも成り立つ. よって,②④より, Focus n=3,5,7, n=1 とすると 1/12=1 Sn=(-1)+12 n(n+1) 場合 この形のままでもよ nが偶数の場合と奇数の場合に分けて考える S2m+1=S2m+a2m+1 練習 一般項am=(-1)n(n+1) で定められる数列の和 B1.27 S„=a+a2+α+... + α を求めよ. ***

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英語 中学生

根気強く英文読める方お願いします🙏 この問題の(2)は合っているでしょうか。 違うのなら違う理由も教えてくれるととても嬉しいです😭お願いします

TREK [3] 9分 10 2935 受験 難問 次の英文を読んで、あとの(1)~(3)の問いに答えなさい。('13 神奈川県) Brian is a high school student from America. He joins a *volunteer club at school. Last Sunday he went to a "nursing home with his friends to teach the old people living there about computers. Mr. Doi, one of the old people there, is talking with Brian in a room at the nursing home. sdgoon 5 Mr. Doi: Hello, I am Kazuo Doi. Nice to meet you. Thank you for coming today. Nice to meet you, too. My name is Brian. What can I do for you, Mr. Doi? Brian Mr. Doi: Can you teach me how to send e-mails, Brian? Brian Mr Doi : Brian Of course, I can. Do you want to send an e-mail to anyone? Yes. One of my friends lives in a nursing home in Hokkaido. I have not seen her for a long time, but she sent me a "postcard last summer. She wrote her *e-mail address on the postcard. I want to send her an e-mail to say "Hello," but I don't know how to do it. salad : Don't worry, Mr. Doi. It is not difficult to send an e-mail. Tellsafi Two days later, Brian and his friend Yumi are talking in their classroom. 15 Yumi Brian Yumi Brian : 20 Yumi : Brian, I hear you went to a nursing home last Sunday, right? : Yes. I went there to do *volunteer work with my friends. : That's great. What did you do there? odon of d We taught the old people living there about computers. They were very glad to learn how to use computers. What did you teach them about computers? I taught some old people how to send e-mails. Mr. Doi was one of them and Brian : his English was good. Read this e-mail from him. He sent it to me yesterday. Brian and Yumi are reading the e-mail from Mr. Doi. Hello, Brian, 100 living here enjoy it. I am sending this e-mail with a picture of me *in front of a microphone." Her e-mail was *encouraging to me. Now I have found an important thing to me. It is to try new things. When I find a new thing to try, I will send you an e-mail again. 35 Kazuo Doi After reading the e-mail from Mr. Doi, Yumi and Brian are talking again. Yumi Mr. Doi enjoys *communication by e-mail. Brian Yes. I'm very happy to hear that. Yumi You did a good thing, Brian. 40 Brian Yumi Brian 45 Yumi : Brian Yumi 50 Brian Yumi 55 Brian T Thank you for coming last Sunday. Do you remember my friend who sent me a postcard with her e-mail address? After I sent her an e-mail, she sent me an e-mail back soon. Using e-mail is a lot of fun. In her e-mail she said, "Now I am trying a new thing in my nursing home. I am *in charge of an announcement over the PA system for 10 minutes in the morning. During this time, I read the *newspaper of the day and make some *comments. Many people Yumi Thank you, Yumi. I went to the nursing home to teach the old people there about computers, but I also learned something there. : What is it, Brian? Mr. Doi knew his friend was in charge of an announcement over the PA system, and then he started to think about trying a new thing, too. I know. Mr. Doi says, "encouraging" in his e-mail. Right. When I taught him how to send e-mails, he said, "I have wanted to learn a lot of things. Using e-mail is one of them." I see. You want to say the e-mail from his friend made him more *positive, right? That's right. First, Mr. Doi learned how to send e-mails and wrote an e-mail to his friend. Next, he got an e-mail from his friend and knew his friend was trying a new thing. Now Mr. Doi ( ) to him. Mr. Doi thinks that it is to try new things. We can say it is good to know how our friends are doing. It is wonderful to *communicate with other people, Brian. : I think so, too. Communicating with other people can make people more positive. I learned that from volunteer work in the nursing home. : I hope that Mr. Doi can find a new thing to try. Please tell me when you get an e-mail from him again. (注) volunteer club ボランティアクラブ nursing home 老人ホーム send〜 〜を送る postcard 絵はがき e-mail address 電子メールアドレス (約 685 語) volunteer work ボランティア活動 in charge of an announcement over the PA system 館内放送を担当して comments コメント in front of a microphone マイクの前の communication by e-mail 電子メールによるコミュニケーション communicate with ~ ~とコミュニケーションをとる newspaper encouraging 励みになる positive 前向きな

解決済み 回答数: 1