Question

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

Answer 1

Answer:

207

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

$S_{18}$ = $\frac{18}{2}$ [ (2 × 37) + (17 × - 3) ]

     = 9( 74 - 51)

     = 9 × 23

     = 207