SOLUTION: An arithmetic sequence is given by 5, 8, 11, .... Write down the value of d. Find I. u100 II. S100 Given that un = 1502, find the value of n.

Algebra ->  Sequences-and-series -> SOLUTION: An arithmetic sequence is given by 5, 8, 11, .... Write down the value of d. Find I. u100 II. S100 Given that un = 1502, find the value of n.       Log On


   

Question 1097029: An arithmetic sequence is given by 5, 8, 11, ....
Write down the value of d.
Find
I. u100
II. S100
Given that un = 1502, find the value of n.
Answer by stanbon(75887) About Me  (Show Source):
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An arithmetic sequence is given by 5, 8, 11, ....
Write down the value of d.
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d = 8-5 = 3
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Find
I. u(100) = u1+99d = 5+99*3
II. S(100) = (100/2)(5+5*99*3)
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Given that un = 1502, find the value of n.
u(n) = 5 + (n-1)d = 1502
(n-1)3 = 1497
n-1 = 499
n = 500
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Cheers,
Stan H.
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