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数学 高校生

青チャートの数列の範囲です。 青い線を引いてるところなのですが、なぜすべてのnについて成り立っていないとダメなのでしょうか? なんとなくはわかるのですが、明確な意味がわかりません。教えてください。

厚本例題125 連立漸化式 (1) 教列(an), {bn} をa=bi=1, an+1=Qn+4bn, bn+1=an+bnで定めるとき 575 O0 txbn+1=y(an+xb») を満たす x, yの組を2組求めよ。 数列 {an), {b»} の一般項を求めよ。 計>本間は,2つの数列{an}, {bn} についての漸化式が与えられている。 このようなタイプで D an+1 にお 【類埼玉大) フみ、 こ生 は,次の2つの解法がある。 「解法1] 等比数列 {a,+kb,} を利用する。 【解法2](an を消去 して, 数列{bn}の隣接3項間の漸化式に帰着させる。 (1)は,数列 {an +xb»} が等比数列となるための条件を求めさせている。よって, [解法1] 公あ 3章 16 の方針で解く。 CHART 連立漸新化式 an+1+.cbn+1=y(an+xb,)の形を導き出す 解答 a+a+xbn+1=Qn+4bn+x(an+bn) =(1+x)an+(4+x)bm よって, ag+1+xbn+1=y(an+xb») とすると 7(1+x)an+(4+x)bn=yan+xybn これがすべてのnについて成り立つための条件は 1+x=y, 4+x=xy x=4 参考 [解法2] [1つの数列 に関する漸化式に帰着させ る]の方針による解答 an+1=an+4bn………… 0 bn+1=an+bn 2から an=bn+1-bm, an+1=bm+2-bn+1 これらをOに代入して ゆえに よって x=±2 bn+2-26n+1-3bm=0 ゆえに これは隣接3項間の漸化式。 特性方程式x-2.x-3=0を 解くと x=-1, 3 よって、p.572 基本例題 123 (1)と同じ方針で、 まず一般項 2 (1)から Yet+262ま=3(a+26»), a.+2b、=3; -26n+ニー(a,-26,),、a.-2b、=-1 よって,数列 {an+26,} は初項 3, 公比3の等比数列; 数列 {an-26,}は初項 -1, 公比 -1の等比数列。 ゆえに bnを求める。 の, an+26,=3·37-1_3" an-26,=ー(-1)"-1= (11)" のt2-2から 40, 2を an, b。の連立方 程式とみて解く。 a,ミ 2 アリートから bn= 4 このタイプの漸化式は,まず2つの新化式の和·差をとってみると,うまくいく場 もある(b.589 EXERCISES 87 (1) 参照)。 -6h bat=an+7bn で定めるとき |種々の漸化式

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英語 高校生

以下の写真はソフィー・ハウの「世界をより良くするための教訓」という文章の一部なのですが、オレンジで線を引いた部分をどのように訳せば良いか分からないため、教えてください。 hold someone to accountで「~に責任を問う」ということから、「そのゴールは私によ... 続きを読む

Wales is a small but progressive country, the only country in the world to have legislated to protect the interests of future generations, the only country to have appointed someone independent to oversee this. Across the world, our systems of government, of politics, of economics have tended to act in the short term. And often, the decisions that are taken discount the interests of future generations and the planet. But in Wales, we're trying to change that by passing a law which requires not just our government but all of our main public institutions to demonstrate how they're acting for the long-term and how the decisions they take don't harm the interests of those yet to be born. And so as a mum of five and the world's only future generations commissioner, I want to share with you today some of the lessons we've learned about how we're trying to leave the world better than we found it. First of all, you must involve people in setting long-term goals. Ask them: What's the Wales or the world you want to leave behind to your children and your grandchildren? We held a national conversation -- the Wales We Want -- and people told us, "We want a low- carbon economy. We want you to help us keep people well rather than just treat them when they're ill. We want connected communities and a more equal Wales." And our government legislated to set seven national well-being goals to achieve that. Each institution has to demonstrate how they're meeting those goals, and they're held to account by me. You have to focus on the interconnections between different aspects of well-being. You need to talk often about why it's just as important to public health as it is to the environment to tackle high levels of air pollution, why diversity in the workforce is just as important to economic prosperity as it is to addressing inequality. Our institutions have a legal duty to act beyond their immediate remit to recognize those connections, work with unusual suspects. And so we're seeing hospitals in Wales working with the National Botanic Gardens to create spaces for nature on their sites. We're seeing offices in our environmental agency helping to find solutions to tackle childhood

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英語 中学生

これの(ア)に入るの何ですか? 早急にお願いします🤲

4 中学生の真紀 (Maki), 順子(Junko)と彼女たちの英語の教師であるナンシー (Nancy)の三人が、 町のフリーマーケット(Flea Market)の会場で会話をしています。 次の会話文を読んで, あとの(1) から(4)までの問いに答えなさい。 o Maki: Hello, Nancy sensei. Nancy:【a 11|ア No, not yet. But I often get some good things at this market. Junko:【b 】 メHi, Maki. Oh, Junko is here, too. Nancy:【 1月ウ It looks nice. How about you, Maki ? Did you also get that bag C Junko: 【d 】オ here ? Nancy:【 17ズ Hello, Nancy sensei. Did you find anything good today ? e Maki: No, I オ Me, too. I got this bag here last Sunday. bought this at a department store. TodayIcame here for the first time. Junko called and told me about this market last night. So I came. I'm so( A) because there are so LIGG many people and so many different things here. Nancy: Yes, so many things. We can find good things we can still use here. But these days, there are some people who throw those things away. Maki: Right. I always feel sorry when I see such things at garbage stations. 2て使い方 Junko: I think we should use things for a longger time and think about how to use 私するべき使ラその 彼らば! them ( ア ). Nancy: That's true. We should reuse more and more. ns cb ofw slacog on sn T Maki: Pardon me ? You said “re . 2p d山w latreaod sd ot o dao slaus Nancy: I said “reuse." ag tph hi eh sdwagsd lsst slaeo Maki: Oh. I remember. We learned that word in your class last week. We also learned the T0 S010001 sucone word “recycle," right ? Nancy: Yes. If we are more interested in reusing and recycling, we won't see so many things on garbage days. Junko: I agree. Well, Nancy sensei, my mother has a booth here today. Would you (2 ode ofdei srl (イ) to come to her booth with us ? Nancy: Sure. Let's go. (注) market マーケット, 市場 garbage station ごみの集積場 garbage day こごみの日 u donm no booth (市場などの)売店 sol ont spo aligog to il dh 三語[第5回]

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