Question

the first term of an arithmetic sequence is -27. the common difference of the sequence is 6. What is the sum of the first 30 terms

Answer 1

Answer:

1800

Step-by-step explanation:

The sum to n terms of an arithmetic sequence is

$S_{n}$ = $\frac{n}{2}$ [ 2a₁ + (n - 1)d ]

where a₁ is the first term and d the common difference

Here a₁ = - 27 and d = 6, thus

$S_{30}$ = $\frac{30}{2}$ [ (2 × - 27) + (29 × 6) ]

     = 15( - 54 + 174)

     = 15(120)

     = 1800