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英語 高校生

なぜ22番の答えが1なのかわかりません わかる方いらっしゃったら解説お願いしますm(_ _)m

2 次の英文A、Bを読み、その文意にそって(21) か ら(26) ま での A その番号を解答用紙の所定欄にマークしなさい。 )に入れるのに最も適切なものを 1,2、3、4の中から一つ選び、 /6 Cycles of Changece The bicycle is an efficient means of transportation. It was invented in the 19th century, and since then, it has been improved many times. Recently; electric bicycles, or "e-bikes," have become widely used. Unlike a regular bicycle, an e-bike has a motor, which allows the rider to go up hills more easily. Sqme cycling fans think that it is "cheating"” to use a bike with a motor. Nevertheless, e-bikes are quickly ( 21 ). In fact, e-bike sales in the United States were eight times greater in 2018 than in 2014 according to one survey. Researchers say this is good news. They claim that e-bikes may have a positive effect on people's health and the environment. One major advantage of e-bikes is that older people and those who do not exercise regularly can cycle. This makes it easier for them to commute to work by bike, which is better for the environment than traveling by car. ( 22 ), e-bikes allow more people to cycle as a hobby. People who could not ride along rough roads or up mountains, for example, can now do so. p Some cycling experts, however, point out problems with the increased use of e-bikes. For one, riders of e-bikes are more likely to be involved in accidents. In response, some people want speed limits to be lowered and other measures to increase safety, such as bike paths. Most importantly, experts say riders of both e-bikes and regular bikes should be careful. It does not matter if a bike has a motor or not. The important thing is to enjoy cycling ( 23 ). 2 causing new problems 4 improving the environment (21) 1 reducing electricity use 3 growing in popularity 3 By contrast, 4 Despite this (22) What is more_ 2 Therefore 2 together with friends 4 while staying safe (23) 1 during the warm months 4 3 in order to keep fit 13の他 21たっク曜師に 4z070も copyright2021 公益財団法人日本英語◆ *ます

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数学 大学生・専門学校生・社会人

この問題の問題13-1(3)(4)、問題13-2の解答を作ってください! お願いします!

2021年 物理学演習2 第13回 デルタ関数 関数f(x)がどのような関数であっても次のような関係を満たす8(x) をデルタ関数という。 「r86) = f0) JO (x * 0) l0(x = 0) 8(x) = このデルタ関数は物理学者の P.A. Dirac によって発明された。名前に関数とついているが、正確 には関数ではなく汎関数の一種の超関数で、線型性と連続性などを満たした汎関数である。 関数: 数 → 数 例えば x → y=f(x) 汎関数:関数 → 数例えば f(x) → f(0) = Sf(x)6(x)dx デルタ関数は関数では無いが、実際には下記のような関数の極限とみなすことができ、どの表現も 同等である。 8(x) = lim 8,(x), ど→+0 8,(x) = {o (x> £/2) 1 28 8(x) = lim 8,(x), E→+0 6,(x) = 2x?+ 2 1 8(x) = lim 8,(x), ど→+0 6(x) = e VTE 8(x) = lim 8,(x), 1 8,(x) = 「e-ddk Zt J-o 1(x2 0) lo (x < 0) 8(x) = 0'(x), 0(x) = 3次元のデルタ関数は以下のように1次元のデルタ関数の積になる。 8(r) = 6(x)6(y)8(z) (o (x =y=z= 0) lo (x =y=z=0以外の場合) 8(r) = 問題13-1 f(x)はx| → oで0となるなめらかな関数とする。デルタ関数8(x) f(x)6(x - a)dx= f(a) について次の性質を証明しなさい。 (1) x6(x) = 0 (2) 6(ax) = )(a>0) (3) 6(x) = 0°(x) so (x< 0) l1 (x> 0) 0(x)は階段関数(ヘビサイド関数)であり、e(x) = である。 {8(x - a) + 6(x + a)}(a> 0) 問題13-2 正規分布を表す次式 = (x)9 がa→ +0 のときにデルタ関数となることを証明しなさい。 1 -exp V2To 2g2

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