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Home >All Categories > Science & Mathematics >Mathematics >Open Question Amanda V Member since:December 30, 2008Total points:182 (Level 1)the sum of the first 35 terms if an arithmetic series is 6090. the 12th term is 114. find the first and 35th term. thanks! have to use the explicit formula and the sum formulaAnswer Question

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Let a[n] be the sequence.

Then a[n] = a[1] + (n-1)d where d is the common difference.
a[1] = 5

10 = a[5] = a[1] + 4d = 5 + 4d
4d = 5
d = 1.25

So the sequence is
5, 6.25, 7.50, 8.75, 10

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