Выражение
1. (x - 3)(x + 3) - x(x - 5).
2. (a + 2)^2 + a(a - 7)(a + 3).

1) (x - 3)(x + 3) - x(x - 5) = x² - 9 - x² + 5x = 5x - 9

2) (a + 2)² + a(a - 7)(a + 3) = a² + 4a + 4 + a(a² - 4a - 21) = a² + 4a + 4 + a³ - 4a² - 21a = a³ - 3a² - 17a + 4

1. (x - 3)(x + 3) - x(x - 5) = 5х - 9.

2. (a + 2)² + a(a - 7)(a + 3) = а³ - 3а² -17a + 4.