(定给好评) (a-b-2c)的平方,怎么求(过程)
问题描述：
(定给好评) (a-b-2c)的平方,怎么求(过程)
答
(a-b-2c)^2=[a-(b+2c)]^2=a^2-2a(b+2c)+(b+2c)^2=a^2-2ab-4ac+b^2+4bc+4c^2
(定给好评) (a-b-2c)的平方,怎么求(过程)
(a-b-2c)^2=[a-(b+2c)]^2=a^2-2a(b+2c)+(b+2c)^2=a^2-2ab-4ac+b^2+4bc+4c^2