数学557 views·Updated Jun 23, 2026·1 page

因数分解と展開の基礎解説 - 例題付き

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数学の基本的な計算問題を通して、式の展開や因数分解の基礎を学ぼう。これらの技術は高校数学の土台となる重要なスキルだ。

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# 数学工
レポート①
係教:ひ、足してある個数指教・「かけてわかる個数
atara
axa
1
Px4322
10 21 X
$x²+3x-1$
(1) 20736-2a+b
=(a+a)+(b+b+b)-(a+a)+b
=a+a+b+b+b-a-a+b
(2)(x-2)(x

式の展開と計算の基礎

数学の計算って難しく見えるけど、実はパターンを覚えれば簡単にできるようになる。式の展開は括弧を外して計算することで、いくつかの基本的なルールがある。

和と差の積の公式 $a+b$ $a-b$ = a²-b² は特に重要だ。例えば $x+5$ $x-5$ = x²-25 のように、真ん中の項が消えてシンプルになる。この公式を使えば計算がぐっと楽になるよ。

二乗の計算も覚えておこう。 $x-11$ ² = x²-22x+121 のように、 $a-b$ ² = a²-2ab+b² の公式を使って展開できる。パターンを覚えれば、複雑に見える式も手順通りに解けるから安心して。

ポイント: 公式を丸暗記するより、なぜそうなるのかを理解すると応用が利くよ！

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