已知:(a+2004)(a+2006)=2005求(a+2005)^2的值

(a+2004)(a+2006)=(a+2005-1)(a+2005+1)
=(a+2005)^2-1=2005
所以(a+2005)^2=2006

∵(a+2004)(a+2006)
=[(a+2005)-1][(a+2005)+1]
=(a+2005)^2-1
=2005
∴(a+2005)^2=2005+1=2006

(a+2005)^2=a^2+2005*2*a+2005*2005
(a+2004)(a+2006)=a^2+(2004+2006)a+2004*2006=2005
2005*2*a=(2004+2006)a 剩下的你就应该会了的

(a+2004)(a+2006)
=[(a+2005)-1][(a+2005)+1]
=(a+2005)^2-1
=2005
所以：(a+2005)^2=2006

(a+2004)(a+2006)
= [(a+2005)-1][(a+2005)+1] 平方差
= (a+2005)^2-1
因为(a+2004)(a+2006)=2005
所以 (a+2005)^2-1=2005
所以（a+2005)^2＝2006