Answer:
see explanation
Step-by-step explanation:
(a)
[tex]S_{n}[/tex] = 1 + 2 + 3 + 4 + 5 + ..... ( to n terms ), that is
∑ n ( for r = 1 to n )
∑ n = [tex]\frac{1}{2}[/tex] n(n + 1) = [tex]S_{n}[/tex]
(b)
[tex]S_{30}[/tex] = [tex]\frac{1}{2}[/tex] × 30 × 31 = 465
