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数学 高校生

青チャート 数2 不等式の証明 例題29(3) 黄色マーカー部の箇所で、なぜ|b+c|が|b|+|c|になったのか分かりません。 (1)の結果をもう一度利用と書いてありますが、そもそもそこが理解できません。なので(2)も場合分けで考えました。 (1)を利用するの意味を教え... 続きを読む

MAKE 52 XX 基本例題 29 絶対値と不等式 次の不等式を証明せよ。 (1)a+b≧a|+|6| (2)|a|-|6|≦la+b] (3)|a+b+cl≦|a|+|6|+| 基本28 重要 30 指針 > (1) 例題 28 |A= A を利用すると、 絶対値の処理が容易になる。 そこで ......... ABA'≧B'⇔A'-B'≧0 A≧0, B≧0のとき の方針で進める。また、絶対値の性質 (次ページの①〜⑦) を利用して証明してもよ (2),(3) 似た形である。 そこで, (1) の結果を利用することを考えるとよい。 CHART 似た問題 1 結果を利用 ②2 方法をまねる 解答 (1) (a+b)²-|a+b|²=a²+2|a||b|+b²-(a²+2ab+b²) =2(abl-ab)≧0 |a+b≤(a+b1)² よって la+b≧0,|a|+|6|≧0から |a+6|≦|a|+|6| 別解] 一般に,|a|≦a≦|a|-|66|6| が成り立つ。 この不等式の辺々を加えて -(|a|+|6|)≦a+b≦|a|+|6| したがって la+6|≦|a|+|6| (2) (1) の不等式でαの代わりに a +6, 6 の代わりに -6 と おくと (a+b)+(-6)≦la+6+1-6| よって |a|≦a+6|+|6| [別解] [1] |a|-|6| <0のとき ア ゆえに |a|-|6|≦la+61 a+b≧0であるから, |a|-|6|< la +6は成り立つ。 [2] |a|-|6|≧0のとき よって |a+6-(|a|-|6|²=a²+2ab+b²-(α²-2|a||6|+62) =2(ab+lab)≧0 よって (la|-|b|)² ≤|a+b|² |a|-|6|≧0,|a+b≧0であるから [1], [2] から la|-|b|≤|a+b| (3) (1) の不等式でもの代わりにb+c とおくと la+b+c)|≦|a|+|b+cl la+b+cl≦|a|+|6|+|c| ≦|a|+|6|+|c| |a|-|6|≦|a+6| 8800000 4 at ◄|A|²=A² |ab|=|a||6| この確認を忘れずに。 |A|≧A, A≧-A か |-|A|≦a≦|A| -B≦A≦B ⇔ [A]≦B <ズーム UP 参照。 <|a|-|6|<0≦la+6 [2] の場合は, (2) 左 右辺は0以上であるから (右辺) (左辺)≧0を示 す方針が使える。 練習 (1) 不等式√²+2+1√x²+y²+1≧lax+by+1」を証明せよ。 ③29 (2) 不等式|a+b|≦|a|+|6|を利用して,次の不等式を証明せよ。 (ア) |a-6≦|a|+|6| (イ) |a|-|6|≧|a-6102 (1) の結果を利用。 (1) の結果をもう1回利用 (|b+cl≦|6|+|c) Cp.60 EX19 ズーム UP その内 絶対値 数学Ⅰで いて € なわち, 絶対値を 例題 29 に (証明で が多く煩 そこで, ~ (1) 指針 ない。 例題28 (2) 左辺 lal-le いが, 証明 とみ ここ (3) は, (1) 参考 (1). 例題 29 (1) 等号 すなわ (2) 等号7 の代わ (3) 等号7 おいた a(b+c) また, よって,

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数学 高校生

英語の長文ってどうやったら読めるようになりますか

1 次の英文を読んで、問 (1) ~ (5) に且本語で答えなさい。 Lobola is the African custom of paying fora bride. Although it is an old custom, not In fact, it is being debated in Botswana. everyone in African cultures is happy with it. Many people, including many women, support payment of lobola. They explain that in Tswana culture, a marriage means joining a family, not just marrying an individual. The idea of marrying into a family is very African. just the man.Through marriage, the young woman's family loses their daughter as she then becomes a part of her husband's family. Lobola is a way to show thanks. It is a form of generosity in African culture. In its traditional form, they also explain, the groom's family gave cattle to the bride's family. But it didn't matter whether the family owned cattle or not. A woman does not get married to A man only had to pay what he could afford if he had no cattle, he could give something else, even the smallest form of payment. The tradition of lobola was a matter of pride. Today, lobola is often given in cash. purchase of a bride. Lobola is meant to join two families together. They know that But its supporters say it is not about the some people abuse the custom. But they believe that the tradition should not be tossed out because it has many positive effects. Rather than get rid of it, many believe it should just be explained better. However, many others say this custom should be stopped. They think it has become commercialized. Families make lots of demands on the groom. They think this makes lobola look very bad. They argue that in Africa's past, a girl was an asset at home. and other household chores. She did the cooking When a family lost that child through marriage, it demanded payment. Today, they think that lobola has changed into a useless tradition. In this custom, a man is buying the right to control a woman. They say women are individuals with rights. In today's world, parents do not have to be paid for a bride because their male and female children are equal. They all work and make contributions to the household. They believe that paying lobola makes it seem like a man is buying a pair of shoes or a bicycle, instead of getting married. They also argue that it is often a financial burden for couples. It is too difficult for many people to pay the price asked. So, is lobola a rich tradition, bringing families together? Or is it an ugly custom of buying women? This debate continues in Botswana, as does the custom.

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