急~！幫我解一題全等式！求ABC既值

L.H.S=(2x-A)(2x+4)-Bx+25
=4x^2+8x-2Ax-4A-Bx+25
=4x^2+(8-2A-B)x+(25-4A)
R.H.S=(x-C)^2+Cx^2
=x^2-2Cx+C^2+Cx^2
=(1+C)x^2-2Cx+C^2
By comparing the likes term on L.H.S and R.H.S
1+C=4 ...(1)
-2C=8-2A-B ...(2)
C^2=25-4A ...(3)

From(1),
1+C=4
C=3

From(3)
C^2=25-4A
9=25-4A
A=4

From(2)
-2C=8-2A-B
-2(3)=8-2(4)-B
-6=8-8-B
B=6



2010-12-31 11:21:31 補充：
我想問下你點整個2次方個2字起右上角==
(x-c)²