Question 631826: i really need help with this! i already got on tutor.com and didnt understand how they explained it! can someone help?!?!
1)Find the sum of the arithmetic sequence 2, 4, 6, 8, ..., 70.
2)Find the sum of the geometric sequence 42, 7, 7/6, .... , 42(1/6)^8
3)find the sum of the first n terms of the sequence. The sequences are either arithmetic or geometric. -1, 11, -121, ...; n = 9
4)find the sum of the first n terms of the sequence. The sequences are either arithmetic or geometric. 14, 8, 2,...; n=9
Answer by ewatrrr(24785)   (Show Source):
You can put this solution on YOUR website!
Hi,
sum of the arithmetic sequence 2, 4, 6, 8, ..., 70.
to Apply**** 
I. determine d= 2 and n = 35 |note: 70 =  as 
II. Substitute values found into to find Sum requested
 Do calculation
14, 8, 2,...; n=9 same as above Steps
sum of the geometric sequence -1, 11, -121, ...; n = 9
to Apply****
I. determine r and n
II. Substitute into Formula
Recommend Posting the Geomteric Sequences separately
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