Question

What is the sum of the arithmetic sequence 140, 133, 126…, if there are 33 terms?

Answer 1

\[Sn=(a1+an)*n/2\]
an=a1+(n-1)*r
r=7

Answer 2

d here is -7. Therefore, we get:
a33 = 140 + 32(-7) = -84.
So, we substitute in the Sn formula and we get:
Sn = (140 - 84)*33/2 = 924.
If I did not make any careless mistake.

Answer 3

thankss