Zadanie 3. Oblicz
[tex]a) \ \sum_{i = 1}^{4} \ i\\\\b) \ \sum_{i = -5}^{-3} \ i^{2}\\\\c) \ \sum_{i = 1}^{100} \ i - \sum_{i = 3}^{101} \ i\\\\d) \ \prod_{i=1}^{3} \ \frac{1}{i}[/tex]