Answer:
S₄₀ = 2780
Step-by-step explanation:
there is a common difference between consecutive terms in the sequence, that is
14 - 11 = 17 - 14 = 3
this indicates the sequence is arithmetic with sum to n terms
[tex]S_{n}[/tex] = [tex]\frac{n}{2}[/tex] [ 2a₁ + (n - 1)d ]
where a₁ is the first term and d the common difference
here a₁ = 11 and d = 3 , then
S₄₀ = [tex]\frac{40}{2}[/tex] [ (2 × 11) + (39 × 3) ]
= 20( 22 + 117)
= 20 × 139
= 2780
