✔ 最佳答案
Ax^2-Ax+Bx^2-B+Cx^2+Cx=x^2+4
(A+B+C)x^2+(-A+C)x-B=x^2+4
so,
A+B+C = 1 --- eq. 1
-A+C = 0 --> A=C
-B=4 -->B=-4
therefore, eq.1 --> 2A = 1+4 --> A = 5/2 = C
A=5/2 , B= -4, C= 5/2
Ax(x-1)+B(x+1)(x-1)+C(x+1)x=x^2+4
Ax^2-A+Bx^2-B+Cx+C=x^2+4
(A+B)x^2+(C-A)x+(C-B) = x^2+4
Therefore, by Observation,
Eq 1: A+B =1
Eq 2: C-A=0
Eq 3: C-B=4
Eq 2 - Eq 3 , we have A-B=4 , B = A-4
Sub B =A-4 into Eq.1
A+A-4 =1
2A=5
A=2.5
Therefore, B = -1.5
Therefore, C = 2.5