Solving for a variable | Linear equations | Algebra I | Khan Academy

Solving for a Variable

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p=2l+2w を lについて解きましょう。

これは、

四方形の周囲の公式です。

周囲は、高さの２倍と

長さの２倍に等しいです。

ここでは、

この式を lについて解きます。

pは２ l＋２wで

lについて解きます。

すべての lを　式を一方に置き

ここでは、右においておくことにしましょう。

そして、２wをなくします

この右の２wを取り除くには

右から２wをひいて

同様に左からも

２wをひき、等式を維持します。

左から２wをひくと

p−２wです。

そして、右は２wが打ち消され、

２lが残ります。lで解くには

両辺を２で割ります。

両辺を２で割ると

右にはlが残り

（p−２w）／２＝l

書き換えると

l＝（p−２w）／２

以上です。