等差数列と等比数列は、数学で最も重要な数列の基本パターンだよ。この2つをマスターすれば、数列の問題がぐっと解きやすくなるんだ。
算数45 views·Updated Jun 4, 2026·1 page等差数列・等比数列の基本と公式
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等差数列と等比数列の基本
等差数列は、隣り合う項の差が一定の数列のこと。例えば、2, 5, 8, 11, 14...のように、毎回3ずつ増えていく数列だね。この一定の差を公差と呼ぶよ。
等比数列は、隣り合う項の比が一定の数列。3, 6, 12, 24, 48...のように、毎回2倍になっていく数列が代表例だ。この一定の比を公比と言うんだ。
どちらも規則性があるから、一般項の公式を使えば任意の項を簡単に求められる。テストでは公式を正確に覚えて、素早く計算することが勝負になるよ。
ポイント: 等差数列は「足し算・引き算」、等比数列は「かけ算・わり算」で規則性を見つけよう！
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算数45 views·Updated Jun 4, 2026·1 page等差数列・等比数列の基本と公式
等差数列と等比数列は、数学で最も重要な数列の基本パターンだよ。この2つをマスターすれば、数列の問題がぐっと解きやすくなるんだ。
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等差数列と等比数列の基本
等差数列は、隣り合う項の差が一定の数列のこと。例えば、2, 5, 8, 11, 14...のように、毎回3ずつ増えていく数列だね。この一定の差を公差と呼ぶよ。
等比数列は、隣り合う項の比が一定の数列。3, 6, 12, 24, 48...のように、毎回2倍になっていく数列が代表例だ。この一定の比を公比と言うんだ。
どちらも規則性があるから、一般項の公式を使えば任意の項を簡単に求められる。テストでは公式を正確に覚えて、素早く計算することが勝負になるよ。
ポイント: 等差数列は「足し算・引き算」、等比数列は「かけ算・わり算」で規則性を見つけよう！
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content in 算数
6Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user