(2a-b-3c)(-2a—b+3c)

问题描述:

(2a-b-3c)(-2a—b+3c)

(2a-b-3c)(-2a—b+3c)
=[-b+(2a-3c)][-b-(2a-3c)]
=b^2-(2a-3c)^2
=b^2-4a^2+12ac-9c^2