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数学 高校生

(1)でこのやり方でやったらダメな理由を教えてください

「基本 例題 178 対数の表現 ①の (1) log23=a, log35=bのとき, 10g210 と 10g 1540 を a b で表せ。 1 (2) logxa= " logx b= 3 logxc= 8 1 24 のとき, 10gabecxの値を求めよ。 [名城大] [久留米大] (3) a,b,c を1でない正の数とし, logab=a, logbc=B, logca=yとする。 このとき, aβ+By+ya= 1 1 _+ + a B 1 r が成り立つことを証明せよ。 基本 177 指針 (1)10, 15, 40 をそれぞれ分解して,2,3,5の積で表すことを考える。 log210=logz(2.5)=1+10g25 底の変換公式を利用して, 10g25をα 6で表す。 また, 101540 は, 真数 40=52 に着目して2を底とする対数で表す。 (2)10gabcx= 1 logx abc である。 logxabc の値を求める。 (3) 右辺を通分すると, 分母に aβy が現れる。 これを計算してみる。 (1)10g210=10gz (2.5)=log22+log25=1+log25 建答 ここで log25= log35 log32 =log23.10g35=ab log32= 10g23 よって log210=1+ab 前ページ検討も参照。 log240 また log 15 40= log2(5.23) log25+3 == log2 15 log2(3.5) log25=ab (前半から) log2 310g25 = ab+3 ab+3 = a+ab a(b+1) (2)10gxabc=logxa+10gx6+10gxc= 1 1 1 + + 3 8 || 24 12 よって logabc x= =2 logx abc (3) + + a 1 B 1 Y aβ+By+ya aby aβy=logablog.clogca=logab• ① loga C =1 2 log. = (3)別解 1 log■ aβ=logablog.c=log 同様に βy=log.a logab logac ra=logcb 1 1 1 したがって であるから,①から + + a B =aβ+By+ya が成り Y 立つ。 したがって, 等式は証明された。 (左辺) =logac+log.a+log =1+1/+1/ B

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英語 中学生

答えはイなのですが、アが×な理由が分かりません。 教えてください。

7 次の(1),(2)の英文を読んで、それぞれの問いに答えなさい。 (1) みなみ市 (Minami City) に住むユイ (Yui)とジョン(John) は、 留学について調査し, 英語でプレ ゼンテーション(presentation) を行いました。 ユイがスライド (Ade)を使って発表をしています。 Hello, everyone. Are you interested in studying abroad? Zealand to study English last summer. I went to New It was an amazing experience for me during those ten weeks. I believe that studying abroad is very meaningful for high school students. Now, please look at Slide 1. It shows the number of Japanese high school students studying abroad from 2009 to 2019. The number went down once in 2015, but in 2017, the largest number of students, more than 45,000, studied abroad. In 2019, the number went down a lot because of big international problems, but we believe that more students will study abroad in the future. So, where did many students go? Look at Slide 2. It shows the countries that the high school students in Minami City went to from 2009 to 2019. We can see that more than half of the students went to English-speaking countries This means that many students used English during their stays. I think that we can improve our language skills by communicating with local people a lot. For example, before studying at a English, but my English (Ave school in New Zealand, I wasn't very good at improv after staying there. But studying abroad isn't easy for everyone. Having friends from abroad is good, but not everyone has that chance. So, how should we study English in Japan? We asked 500 students at this high school, "How do you study English at home?" Look at Slide 3. It shows the results. Among these several ways, we recommend watching movies and TV dramas in English. We think so because by watching them, we can also learn about the people living there and their cultures. Learning these things is as important as learning the English language itself. We think that learning English is very useful for high school students. Study hard, and if you have a chance, please go abroad and learn many things. Slide 2 Slide 3 Ways to Study English % 25% 32% Study with textbooks 62 Watch movies 14 10% Watch TV dramas 14 15% Read English books or newspapers 7 U.S. U.K. Australia ☐ others South Korea Keep a diary in English 3 (注) meaningful 意味のある English-speaking 英語を話す not everyone U.S. アメリカ合衆国 South Korea すべての人が〜とは限らない chance U.K. keep a diary 日記をつける itself それ自体

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