(2a-5b-3c)(2a+5b+3c)求这题咋写?
问题描述:
(2a-5b-3c)(2a+5b+3c)求这题咋写?
答
(2a-5b-3c)(2a+5b+3c)
=[2a-(5b+3c)](2a+5b+3c)
=4a^2-(5b+3c)^2
=4a^2-25b^2-30bc-9c^2