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数学 高校生

黄色マーカーで引いたところが分かりません。 なぜ判別式が0以上になるのですか?

基礎問 8 第1章 式と曲線 2 円(Ⅱ) JX.CJ だ円 P(x,y)をとり,点Pでの接線 ② 2直線y=1, および, x=2との交点 をそれぞれ, Q, R とする. 点 (2, 1)をAとし, AQRの面積をSとお く.このとき、次の問いに答えよ. (1) +2y=kとおくとき, 積 141 をkを用いて表せ. (2) Skを用いて表せ. (3) PC上を動くとき, Sの最大値を求めよ. (1) 点Pはだ円上にあるので,12+4y²=4 (>0,y>0) をみた しています。 (2) AQRは直角三角形です. (3) のとりうる値の範囲の求め方がポイントになります. 解答は2つありま すが、1つは演習問題1がヒントになっています. 解答 精講 (1) の部分をCで表す。 曲線C上に点 +y²=1のx>0,y>0 mi²+4y²=4 1 (21+2y1) -4.miy=4 x₁y₁= k²-4 4 (2) P(x,y) における接線の方程式は +4yy=4 Q(4-44₁, 1), R(2, 4-20₁ I 4y₁ よって, AQ=2- 4-4y_2cc1+4y-4 X1 X1 AR=1-4-2.12.x+4y-4+2y-2 4y1 y 4y₁ 2y₁ ∴S= S=1/12 AQAR= (+2y-2) __ 2(k−2)2 2x₁4₁ k²-4 Q P x=2 y=1 R 2 x MAT 2(k-2) k+2 x₁+2y₁=k y を消去して (3) (解Ⅰ) (演習問題1の感覚で・・・) | vi'+4y1²=4....① 判別式≧0 だから、 演習問題 2 ・=2- ポイント x₁²+(k-x₁)²=4 2²²2-2k+k²-4=0 8 k+2 k²-2(k²-4) 20k²-8≤0 : -2√2 ≤k≤2√2 また、右図より 11 より だ円 よって, 2<k≧2√2 が最大のときSは最大だから, Sの最大値は6-4√2 |=2cos0 より (0<< とおける. ly = sin0 ∴.k=z+2y=2(sinQ+cos0)=2√/2 sin (0+7) 40+ だから、 // <sin (+4)=1 3π 4 4 √2 ∴.2<k .. 2<k≤2√2 が最大のときSは最大だから, Sの最大値は 6-4√2 +. VB' (0-1) =1 上の点は a² x=acos0y= bsin0 とおける 9 だ円 +g=1と直線y=-1/12+k(k:定数)は,異なる2 点PQで交わっている.このとき, 次の問いに答えよ. (1) 定数kのとりうる値の範囲を求めよ. (2) 線分PQの中点Mの軌跡の方程式を求めよ. 第1章

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英語 中学生

中学生 英語 長文です。 このような長文が全くと言っていいほど分かりません。 どのように解き進めていけばいいのでしょうか。 写真は愛知県マーク模試第4回のものです。

第4回愛知・中3英語 4 次の文章を読んで あとの (1)から(5)までの問いに答えなさい。 Where do you usually buy things? Do you go to stores near your house? Do you visit websites and click "buy now"? Today, many people order some products through the internet and have them delivered to their houses. It's convenient to get delicious food or interesting goods from all over Japan without (A) far from home. Then, have you ever thought about the system of carrying these products? Trucks are the main way of transportation. There are different sizes of trucks and they can go to all types of places. Carrying products by truck is necessary for people's lives. However, they produce a lot of CO2. They produce less CO2 than before and they're becoming more eco-friendly, but just using such trucks is not enough to reduce CO₂ because more trucks are needed to carry more products. To solve this problem, the modal shift began. The modal shift is to change the way of transportation partly from trucks to trains or ships. CO2 produced by trains or ships is less than that by trucks. When you think about the environment, it is better to use trains or ships. There are other good points of the modal shift. When products are carried by train or ship, the cost of transportation goes down. Trains or ships can usually carry more products than trucks. So, I needed to the cost / carry / decrease / will products I as a result. Another good point is the smaller number of operators. Each truck needs one driver. After all, a lot of truck drivers are needed. Trains and ships can carry more products than trucks and they need fewer operators. 1 There is, however, a disadvantage of the modal shift. Trains can move only between stations, and ships can move only between ports. They can't carry products from factories to shops or homes. Products are moved from trucks to trains or ships and from trains or ships to trucks. This takes a lot of time. The modal shift is not a good way to carry fresh products fast. As for ships, When it is bad and they don't move, the products are not carried on schedule. (2) The need for transportation is increasing. And now, there are not enough truck drivers to carry products. It is necessary to change the system of transportation to solve the environmental problem. (注) click buy now" 「今すぐ買う」をクリックする order を注文する have delivered ~を届けてもらう convenient system システム transportation M eco-friendly 環境にやさしい partly 部分的に cost reduce ~を減らす solve ~を解決する modal shift モーダルシフト operator # disadvantage 不便なこと port factory I need t environmental 環境の on schedule 予定どおりに

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英語 高校生

この添削だけでもお願いしたいです🙇‍♂️

Standard Lesson 7 Logic & Expression 2 Try it out 1 下の語を適切な形に変えて、英文を完成させましょう。 1. Sorry, my brother is out now. I will have him 和訳: 2. My parents always tell me |和訳: 3. I heard someone |和訳: 4. My father didn't let me |和訳: Let's Write harder, but I don't like studying. in the crowd. They needed help. you back. to the movies alone. He was so strict. call / go / shout / study / walk Example Bankの例文を参考に,( 1. 初心者がその車を運転するのは危険だ。 (drive / beginners / it's / the car / to / dangerous / for). It's dangerous for beginners to drive the car. 2.その花瓶を割るなんて、彼女は不注意だった。 )内の語句を並べかえて、 英文を完成させましょう。 (the vase/ her/to/careless / break / of / it's). It's was careless of her to the vase. 3.私は皆さんにこのウェブサイトをみてほしい。 (this website / I / see / everybody / to / want ). I want everybody to see this website, 4.彼はその修理工に車を修理してもらった。 (repair/ he / his car / the mechanic / had). He had The mechanic repair his cari 5.先生は文化祭のために何を買うべきかを私たちに決めさせてくれた。 (what to buy/ decide / us / our school festival / let / for / our teacher). Our teacher let us decide what to buy for our School festival. 6. 私は隣の部屋でジムが歌の練習をしているのを聞いた。 (Jim/I/ practice singing/heard / the next room/in). I heard Jim practice singing in the next room. 2 Example Bankの例文を参考に、次の状況でどのように言えばよいか考えてみよう。 1.子供たちは外で運動することが必要だと言いたいとき。 It's necessary for the children to exerciseoutside. 2. あの状況で彼女を助けるとは彼は勇敢だと言いたいとき。 It's brave of he to help her 2 in that situation.

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