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Question
Find the sum of the following Aps:
9, 7, 5, 3 … to 14 terms
Solution
The given AP is 9, 7, 5, 3,……….
Here, a = 9 and d = 7 - 9 = - 2
Using the formula, `s_n = n/2 [ 2a + (n-1) d] ,` we have
`s_14 = 14/2 [ 2 xx9 + (14 -1) xx (-2 )]`
`= 7 xx (18-26)`
= 7×(-8)
=-56
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