$A = x^2 - 2xy + 3y^2$, $B = 2x^2 + 3y^2$, $C = x^2 - 2xy$ のとき、$2(A - B) - \{C - (3A - B)\}$ を計算します。代数学式の計算多項式展開2025/8/101. 問題の内容A=x2−2xy+3y2A = x^2 - 2xy + 3y^2A=x2−2xy+3y2, B=2x2+3y2B = 2x^2 + 3y^2B=2x2+3y2, C=x2−2xyC = x^2 - 2xyC=x2−2xy のとき、2(A−B)−{C−(3A−B)}2(A - B) - \{C - (3A - B)\}2(A−B)−{C−(3A−B)} を計算します。2. 解き方の手順まず、与えられた式を整理します。2(A−B)−{C−(3A−B)}=2A−2B−(C−3A+B)2(A - B) - \{C - (3A - B)\} = 2A - 2B - (C - 3A + B)2(A−B)−{C−(3A−B)}=2A−2B−(C−3A+B)=2A−2B−C+3A−B= 2A - 2B - C + 3A - B=2A−2B−C+3A−B=5A−3B−C= 5A - 3B - C=5A−3B−C次に、A,B,CA, B, CA,B,C の値を代入します。5A−3B−C=5(x2−2xy+3y2)−3(2x2+3y2)−(x2−2xy)5A - 3B - C = 5(x^2 - 2xy + 3y^2) - 3(2x^2 + 3y^2) - (x^2 - 2xy)5A−3B−C=5(x2−2xy+3y2)−3(2x2+3y2)−(x2−2xy)=5x2−10xy+15y2−6x2−9y2−x2+2xy= 5x^2 - 10xy + 15y^2 - 6x^2 - 9y^2 - x^2 + 2xy=5x2−10xy+15y2−6x2−9y2−x2+2xy=(5x2−6x2−x2)+(−10xy+2xy)+(15y2−9y2)= (5x^2 - 6x^2 - x^2) + (-10xy + 2xy) + (15y^2 - 9y^2)=(5x2−6x2−x2)+(−10xy+2xy)+(15y2−9y2)=−2x2−8xy+6y2= -2x^2 - 8xy + 6y^2=−2x2−8xy+6y23. 最終的な答え−2x2−8xy+6y2-2x^2 - 8xy + 6y^2−2x2−8xy+6y2