Question

Help me guys. I don’t get this one. Thank you

Answer 1

207

Explanation:

The sum to n terms of an arithmetic sequence is

`S_(n)` =
`(n)/(2)` [ 2a₁ + (n - 1)d ]

where a₁ is the first term and d the common difference

Here a₁ = 37 and d = 34 - 37 = - 3 , thus

`S_(18)` =
`(18)/(2)` [ (2 × 37) + (17 × - 3) ]

= 9( 74 - 51)

= 9 × 23

= 207