(8) $(x-9y-7)(5x+2y)$ を展開して整理する問題。代数学展開多項式因数分解同類項2025/4/151. 問題の内容(8) (x−9y−7)(5x+2y)(x-9y-7)(5x+2y)(x−9y−7)(5x+2y) を展開して整理する問題。2. 解き方の手順まず、x−9y−7x-9y-7x−9y−7 の各項を 5x+2y5x+2y5x+2y の各項にかけます。(x−9y−7)(5x+2y)=x(5x+2y)−9y(5x+2y)−7(5x+2y)(x-9y-7)(5x+2y) = x(5x+2y) - 9y(5x+2y) - 7(5x+2y)(x−9y−7)(5x+2y)=x(5x+2y)−9y(5x+2y)−7(5x+2y)=5x2+2xy−45xy−18y2−35x−14y= 5x^2 + 2xy - 45xy - 18y^2 - 35x - 14y=5x2+2xy−45xy−18y2−35x−14y次に、同類項をまとめます。2xy2xy2xy と −45xy-45xy−45xy は同類項なので、5x2+(2−45)xy−18y2−35x−14y5x^2 + (2-45)xy - 18y^2 - 35x - 14y5x2+(2−45)xy−18y2−35x−14y=5x2−43xy−18y2−35x−14y= 5x^2 - 43xy - 18y^2 - 35x - 14y=5x2−43xy−18y2−35x−14y3. 最終的な答え5x2−43xy−18y2−35x−14y5x^2 - 43xy - 18y^2 - 35x - 14y5x2−43xy−18y2−35x−14y