1) $$(x + 9)^2 = x^2 + 2 \cdot x \cdot 9 + 9^2 = x^2 + 18x + 81$$
2) $$(3a - 8b)^2 = (3a)^2 - 2 \cdot 3a \cdot 8b + (8b)^2 = 9a^2 - 48ab + 64b^2$$
3) $$(m - 7)(m + 7) = m^2 - 7^2 = m^2 - 49$$
4) $$(6a + 10b)(10b - 6a) = (10b + 6a)(10b - 6a) = (10b)^2 - (6a)^2 = 100b^2 - 36a^2$$
**Ответ:**
1) $$x^2 + 18x + 81$$
2) $$9a^2 - 48ab + 64b^2$$
3) $$m^2 - 49$$
4) $$100b^2 - 36a^2$$