SOLUTION: Find the sum of the first 103term of 18,26,34. .

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Question 1201456: Find the sum of the first 103term of 18,26,34. .
Found 2 solutions by ikleyn, mananth:
Answer by ikleyn(52790)   (Show Source):
You can put this solution on YOUR website!
.

Use the formula for the sum of n first term of an arithmetic progression.

About this formula, look into the lessons
    - Arithmetic progressions
    - The proofs of the formulas for arithmetic progressions
in this site.

Your progression has first term 18, the common difference of 8
and the number of terms 103.

This exercise will only be useful for you, if you will perform it on your own.

Answer by mananth(16946)   (Show Source):
You can put this solution on YOUR website!
Find the sum of the first 103term of 18,26,34. .
26-18=8
34-26 =8
The difference between two consedutive term is 8
So the sequence is an AP
Sum of n terms of AP formula 3
n=103
a first term = 18
d=8
S103 = (103/2)* (2*18 +(103-1)*8
= (103/2)*(36 + 102*8)
= (103/2)*852
= 43,878 the sum of the first 103 terms