S2 Identity (2x - A)(2x+4) - Bx + 25 ≡ (x - C)^2 + Cx^2 求A,B,C的數值?

(2x - A)(2x+4) - Bx + 25 ≡ (x - C)^2 + Cx^2
left=4x^2 +8x -2Ax-4A-Bx+25
left=4x^2+(8-2A-B)+(25-B)
right=x^2 -2Cx+C^2 +Cx^2
right=(C+1)-2Cx+C^2
C+1=4
C=3
25-B=C^2
-B=9-25
B=16
-2C=8-2A-B
-2(3)=8-2A-16
A=1
(A,B,C)=(1,16,3)

A=4
B=6
C=3