What is the sum of the arithmetic sequence 3, 9, 15..., if there are 36 terms? (5 points)

3,468
3,888
4,234
4,572

Question

What is the sum of the arithmetic sequence 3, 9, 15..., if there are 36 terms? (5 points)
 		
	3,468
	3,888
	4,234
	4,572

anonymous · Answer

I just need to know how to do this

hartnn · Answer

so you know the formula to calculate sum of the terms in arithmetic sequence?

hartnn · Answer

$\Large S_n = n/2(2a + (n-1)d)$

a = 1st term
n  = number of terms
d =common difference

hartnn · Answer

the first term is a =3
its given that n =36

you know how to find 'd' , the common difference?

hartnn · Answer

d =2nd term - 1st term = 3rd term - 2nd term = ... and so on...

anonymous · Answer

@hartnn Thank you, ill fan and medal

hartnn · Answer

welcome ^_^ happy to help :) you may go through this tutorial, if you want to: http://openstudy.com/study#/updates/503bb2a0e4b007f9003103b0