Question

Помогите (3х+7у)(3х-7у)=

Answer 1

(3х+7у)(3х-7у).

Формула разности квадратов!

9х²-27ху+27ху-49у² = 9х²- 49у²

Answer 2

$boxed{a^2-b^2=(a+b)(a-b)}\\(3x+7y)(3x-7y)=(3x)^2-(7y)^2=boxed{9x^2-49y^2}$