Question

What is the sum of the arithmetic sequence 9, 14, 19, …, if there are 36 terms?

Answer 1

1º you have to find 36º term.
\[a _{n}=a _{1}+(n-1)d\]
use this formula, where d is the commun diference
2º find the sum using this formula:
\[Sum = (a _{1}+a _{36})/2\]

Answer 2

i got 875 and then doing the second part i guess i screwed up an got 14144 o.o and that's not a choice

Answer 3

First term is 9.
Common difference is 5
The sum of the sequence is given by:
9x + 5x(x - 1)/2
x is the number of terms
When x = 38 the expression gives the value of 3,857

Answer 4

1º step:\[a _{36}=9+35*5=184\]