$(\sqrt{2} + 1)(\sqrt{2} - 7)$ を計算します。代数学式の展開平方根の計算2025/8/91. 問題の内容(2+1)(2−7)(\sqrt{2} + 1)(\sqrt{2} - 7)(2+1)(2−7) を計算します。2. 解き方の手順この式を展開します。(2+1)(2−7)=2⋅2+2⋅(−7)+1⋅2+1⋅(−7)(\sqrt{2} + 1)(\sqrt{2} - 7) = \sqrt{2} \cdot \sqrt{2} + \sqrt{2} \cdot (-7) + 1 \cdot \sqrt{2} + 1 \cdot (-7)(2+1)(2−7)=2⋅2+2⋅(−7)+1⋅2+1⋅(−7)=2−72+2−7= 2 - 7\sqrt{2} + \sqrt{2} - 7=2−72+2−7=2−7−72+2= 2 - 7 - 7\sqrt{2} + \sqrt{2}=2−7−72+2=−5−62= -5 - 6\sqrt{2}=−5−623. 最終的な答え−5−62-5 - 6\sqrt{2}−5−62