Решение:
1) \((p + 8)^2\) = \(p^2 + 2 \cdot p \cdot 8 + 8^2\) = \(p^2 + 16p + 64\)
2) \((10x - 3y)^2\) = \((10x)^2 - 2 \cdot 10x \cdot 3y + (3y)^2\) = \(100x^2 - 60xy + 9y^2\)
3) \((x - 9)(x + 9)\) = \(x^2 - 9^2\) = \(x^2 - 81\)
4) \((4m + 7n)(7n - 4m)\) = \((7n + 4m)(7n - 4m)\) = \((7n)^2 - (4m)^2\) = \(49n^2 - 16m^2\)