Question

разложите на множители

Answer 1

3a:

a^2 - b^2 + a - b = (a - b)(a + b) + (a - b) = (a - b)(a + b + 1);

3б:

x^2 - 2xy + y^2 - c^2 = (x - y)^2 - c^2 = (x - y - c)(x - y + c)

4:

(n - 1)(n^2 + n + 1) = n^3  - 1   Тогда:

-n^3 + 82 + (n - 1)(n^2 + n + 1) = -n^3 + 82 + n^3 - 1 = 82 - 1 = 81 = 9^2 => делится на 9.