(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?

(2a-5b-3c)(2a+5b+3c)
=[2a-(5b+3c)](2a+5b+3c)
=4a^2-(5b+3c)^2
=4a^2-25b^2-30bc-9c^2