Question

докажите тождества (3a-2b)^3 + (3a+2b)^3=18a(3a^2+4b^2)

Answer 1

(3a-2b)^3 + (3a+2b)^3=
=27a^3-54a^2b+36ab^2-8b^3+27a^3+54a^2b+36ab^2+8b^3=
=54a^3+72ab^2=18a(3a^2+4b^2)