Question 1103556
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The 9th term, 49, is 6 terms after the 3rd term, 1.  So 49 is 1 plus 6 times the common difference.  That means the common difference is (49-1)/6 = 8.<br>
The first term is the 3rd term, minus 2 times the common difference: 1-2(8) = 1-16 = -15.<br>
The first term is -15; the common difference is 8.  The explicit formula for the sequence is<br>
(first term) + ((n-1) times the common difference):
{{{t(n) = -15+8(n-1) = -15+8n-8}}}
or
{{{t(n) = 8n-23}}}