Решение:

1. f(5)

   $$f(5) = 5^2 - 19 \cdot 5 = 25 - 95 = -70$$

2. f(-2)

   $$f(-2) = (-2)^2 - 19 \cdot (-2) = 4 + 38 = 42$$

3. f(0)

   $$f(0) = 0^2 - 19 \cdot 0 = 0 - 0 = 0$$

Ответ: f(5) = -70; f(-2) = 42; f(0) = 0