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数学 高校生

数列の格子点の問題です 赤で囲った式がどこからきたのか分かりません💦

3つの不等式x≧0, y ≧0, 2x+y≦n (nは自然数)で表さ れる領域をDとする. (1) Dに含まれ,直線æ=k(k=0, 1,..., n)上にある格子点 (x座標もy座標も整数の点)の個数をkで表せ. (2) Dに含まれる格子点の総数をnで表せ. 114 Σ計算の応用例として, 格子点の個数を求める問題があります。こ れは様々なレベルの大学で入試問題として出題されています。 格子点の含まれている領域が具体的に表されていれば図をかいて数 上げることもできますが,このように,nが入ってくると数える手段を知ら いと解答できません.その手段とは,ポイントに書いてある考え方です. ポイントによれば,直線y=kでもできそうに書いてありますが, こちらを った解答は (別解) で確認してください. 精講 (1) 直線 x=k上にある格子点は (k, 0), (k, 1), , (k, 2n-2k) の (2n-2k+1) 個. 注 y座標だけを見ていくと, 個数がわかります. (2) (1)の結果に, k = 0, 1, ... n を代入して すべ て加えたものが, D に含まれる格子点の総数. Σ (2n-2k+1) b=0 n+1 解答 -{(2n+1)+1} 14y 2n 2n-2k ---- O ◆ 等差数列 |x=k An n ろん, (2n+1)-2として計算してもかまいません。 k=0 IC 等差数列の和の公式 =(n+1) 2 主計算をする式がんの1次式のとき, その式は等差数列の和を表 しているので,17/12 (a+an) () を使って計算していますが、もち

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英語 高校生

英文長くてすみません💦 1番最後のitは何を指しているのでしょうか。署名を集めたことですか?それともプラスチック汚染のことですか?それともその後にHowever,they received no answer from the government of Bali とあるの... 続きを読む

Bye Bye Plastics Scene 1 1 Sisters Melati and Isabel were 10 and 12 years old when they were by a lesson in school in Bali about significant people such as Nelson Lady Diana, and Mahatma Gandhi. They returned home and wondered inspired Mandela, G-1 in 2013 and has now grown into a well-known international movement which "What can we do as children in Bali, NOW, to make a difference?" That was まさに the very beginning of their campaign called "Bye Bye Plastic Bags." It started Scene 2 the gove thanked agreed to 6 In 201 5 but the thought collected says NO to plastic bags. 連結形(well+過去分詞) 平方メートル 2 Bali is known by locals as an island of gods and a green paradise. People in Bali, however, produce 680 cubic meters of plastic garbage a day. Amazingly, this is about the size of a 14-story building, but less than 5% gets recycled. 未満 階 thrown The rest ends up in drains, rivers, and the ocean, or it is just burned or be動詞+過去 away. Such plastic pollution is now damaging the whole island. より動作を強調 remaine and try Scene 4 7 On ban or or pla →理由(既知情報) Tuow 3 Since they were driven by a love of their home and its nature, Melati and Isabel started Bye Bye Plastic Bags in October 2013. Their aim was to put a ban on the use and sale of single-use plastic bags in Bali to stop plastic pollution. Their first efforts focused on giving out non-plastic bags, such as net bags, newspaper bags, and 100% organic material bags, to local shops. They also began to teach locals and let them know about the pollution problems. 取り組み G-2 4 In order to educate all the island on the dangerous effects of single-use plastic bags, Melati and Isabel thought that government policies needed to change. They decided that they should collect one million signatures so that officials would not ignore them. To collect that many signatures, they came up with a great idea: collecting signatures at the very busy Bali International Airport. They went there and talked with officials, but these people wouldn't let them do so at first. The sisters talked again and again, and finally they were allowed to collect signatures there. As a result of this great campaign, they were invited to talk about it on TV programs and also at the United Nations. G-2 Scene 3 pollut 8 M 15 teena of w ed just 9 ar

解決済み 回答数: 2