Question

这道题有人会做吗？急啊！是因式分解。

Answer 1

=(a+b)^2-(b+d)^2+(a+c)^2-(c+d)^2
=[(a+b)+(b+d)][(a+b)-(b+d)]+[(a+c)+(c+d)][(a+c)-(c+d)]
=(a+2b+d)(a-d)+(a+2c+d)(a-d)
=(a-d)(a+2b+d+a+2c+d)
=(a-d)(2a+2b+2c+2d)
=2(a-d)(a+b+c+d)