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Question
Find the sum of the following arithmetic progressions:
1, 3, 5, 7, ... to 12 terms
Solution
1, 3, 5, 7, ... to 12 terms
Common difference of the A.P. (d)
`= a_2 - a_1`
= 3 - 1
= 2
Number of terms (n) = 12
First term for the given A.P (a) = 1
So using the formula we get
`S_n = 12/2 [2(1) = (12 - 1)(2)]`
= (6)[2 + (11)(2)]
= (6)[24]
= 144
Therefore, the sum of first 12 terms for the given A.P. is 144
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