SOLUTION: Write the explicit formula for the arithmetic sequence where t underscore 7 =121 and t underscore 15 =193 .

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Question 1036491: Write the explicit formula for the arithmetic sequence where t underscore 7 =121 and t underscore 15 =193 .
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Write the explicit formula for the arithmetic sequence where t underscore 7 =121 and t underscore 15 =193 .
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t(7) = a + 6d = 121
t(15) = a + 14d = 193
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Subtract and solve for "d"::
8d = 72
d = 9
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Solve for "a"::
a + 6*9 = 121
a = 121- 54
a = 67
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Ans: t(n) = 67 + (n-1)*9 = 67 - 9 + 9n = 58 + 9n
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Cheers,
Stan H.