Answers

2016-06-14T01:33:51+08:00
I think it's 153. 9 + 11 |+ 13 + 15 + 17 + 19 + 21 +23 + 25 = 153



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  • Brainly User
2016-06-14T12:02:37+08:00
Either you identify the odd numbers between 8 and 26 then manually add them, or use the formula of sum of the arithmetic series (as expected in your solution given that this is your Math topic).  

The formula can be used in bigger sets of numbers, that is, using the formula you can add even the given sequence is more than 100 items/terms.

x = {x / x is an odd number between 8 and 26}
x = {9, 11, 13, 15, 17, 19, 21, 23, 25}

n = 9 (number of items in the sequence or term)
d = 2 (common difference between any two consecutive term)
a₁ = 9 (the first term in the sequence)
a₉ = 25 (the 9th and last term in the sequence)

Sum of the series formula:

S{n} =  \frac{n}{2} [2(a₁) + (n-1)(d)]

S₉ = 9/2 [2(9) + (9-1)(2)]
S₉ = 9/2 [ 18 + (8)(2)]
S₉ = 9/2 [18 + 16]
S₉ = 9/2 (34)
S₉ = 9 (17)
S₉ = 153

ANSWER:  S
= 153
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