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数学 高校生

波線部のところなんですが5と近似する意味は何ですか?? というか、なぜ5と近似していいのですか? 5.1761より大きいからそれよりも小さい5より大きいのは確定ということですか? その後の4ⁿ-1>10^5 を4ⁿ>10^5とするのは、1が影響がないくらい小さいからですか... 続きを読む

練習初項が2, 公比が4の等比数列を {an} とする。 ただし, 10g102=0.3010, logio3=0.4771とする。 ④18 (1) a が10000を超える最小のnの値を求めよ。 (2)初項から第n項までの和が100000 を超える最小のn の値を求めよ。 (1)初項が2,公比が4の等比数列であるから an=2.4"-11 2.4-110000 22n-1>104 10g1022n-1>10g10 104 an> 10000 とすると 整理して 両辺の常用対数をとると ゆえに (n-1)10g102>4 よって n> /12/11 2 2 log102 108102 +1 + =7.14...... 1 0.3010 2 この不等式を満たす最小の自然数n を求めて ←an=arn-1 ←2.4" '=2(22)7-1 =2.227-2 ←log1010=410g1010=4 ←log102 0 検討 対数の性質 (数学II) > 0, ¥1, M> 0, N > 0, んは実数 のとき 110gaMN n=8 (2) 初項から第n項までの和は 2(4-1)_2(4"-1) = 4-1 =logaM+logaN 2(4"-1) > 100000 M ①として, 両辺の常用対数をとると 2 loga 3 N 2(4-1) =logaM-logaN log10 ->log10 105 3 3 loga M=klog.M ゆえに よって log10 (4"-1)>5-10g102+10g103 ここで 10g102+10g10 (4-1)-10g103>5 5-10g102+10g103=5-0.3010+0.4771=5.1761 >5=510g1010=10g10105 ゆえに 10g10 (4-1)>10g10 105 よって 4"-1>105 ゆえに 4">105 ② すなわち 22n>105 <4">105+1>105 この両辺の常用対数をとると 2n10g10 2>5 5 ゆえに n> 5 2 log102 2.0.3010 =8.3...... よって、②を満たす最小の自然数nは ここで n=9 2(4°-1)=1/2(4'+1)(4'-1)= 2 3 3 2(49-1) 2=1/12 (2.4°+1)(2・4°-1)=1/23・51 3 =174762>100000 3 ・・257・255=43690 <100000 <48-1-(4)-1 ・・513・511 <4-1-(2.4)-1 2(4"-1) 3 は単調に増加するから, ①を満たす最小の自然数nは n=9

解決済み 回答数: 3
英語 高校生

「But reading isn’t just a nice thing to do – it’s an essential skill,something you need for everyday activities, whether that’s finding o... 続きを読む

Phil Hello. This is 6 Minute English from BBC Learning English. I'm Phil. Beth And I'm Beth. Are you a big reader, Phil? Phil Sure, I enjoy reading - and it's also a great way to pass the time on my daily commute to work. But reading isn't just a nice thing to do - it's an essential skill, something you need for everyday activities, whether that's finding out the news by reading a newspaper or buying groceries by reading the labels. Beth And that's why I was shocked by a recent UN report estimating that around the world over 700 million adults are illiterate, which means they can't read or write. Phil Wow! That's a huge number of people excluded from doing basic day-to-day things. So, what can be done to get more adults reading and writing? In this programme, we'll be hearing about projects in two very different countries trying to do just that. And, as usual, we'll be learning some useful new vocabulary as well. Beth But first I have a question for you, Phil. I mentioned a recent UN report on the high numbers of people unable to read and write, but illiteracy is not a new problem. Since 1967, the UN has been highlighting the importance of literacy, being able to read and write, with a day of celebration called International Literacy Day. But when does it take place? Is it: a) the 8th of March? b) the 8th of June? or, c) the 8th of September? Phil I think International Literacy Day is on the 8th of September. Beth OK, Phil, we'll find out if that's correct at the end of the programme. The biggest reason people grow up illiterate is not going to school, and that's especially true for people living in the coastal towns of Bangladesh. Because these towns flood regularly, families are always on the move, making it hard for children to get an education. Phil The Friendship Project teaches reading and writing to groups of Bangladeshi women and girls. They also teach numeracy which means the ability to do basic maths like counting and adding up. Here one student, Rashida, explains the impact it's had on her to BBC World Service programme, People Fixing The World: Rashida My parents never sent me to school and I've suffered from not being able to read and write. My children were embarrassed that I was illiterate. I couldn't even do basic accounting. Until now, I've had to use my fingerprint as a signature as I was illiterate, but now I can sign my name because I can read and write thealphabet, and I'll also be able to keep an account of my expenses. No one can cheat me anymore. Beth Before the Friendship Project, Rashida couldn't write her signature – her name written in her own handwriting. Instead, she had to use her fingerprint. Now, Rashida has learned the alphabet and also some basic maths, so she knows how much money she's spent, and how much she has left. This means no-one can cheat her, can trick or swindle her into taking her money.

解決済み 回答数: 1