close
標題:
此文章來自奇摩知識+如有不便請留言告知
Form 2數學問題
發問:
If (x+7)(2x-5)≡Ax^2+B(x+2)+C , find the value of A ,B and C.
最佳解答:
Put x= 1, A + 3B + C = -24 ______ (1) Put x= -1, A + B + C = -42 ______ (2) (1) - (2) : 2B = 18, B = 9 (2): A + 9 + C = -42, A + C = -51 ______ (3) Put x= -2, 4A + C = -45 ______ (4) (4) - (3) : 3A = 6, A = 2 (3): 2 + C = -51, C = -53 Therefore, A = 2, B = 9, C = -53
其他解答:
(x+7)(2x-5) =2x^2+9X-35 =2x^2+9X+18-18-35 =2x^2+9(X+2)-18-35 =2x^2+9(X+2)-18-35 =2x^2+9(X+2)-53 =Ax^2+B(x+2)+C so A=2 B=9 C=-53
文章標籤
全站熱搜
留言列表
