Question 1126167
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A solution to the problem using the formal mathematics, as shown by the other tutor, is of course valid.  But if you don't need to show a formal solution, you can get the answer with much less work.<br>
The 1st term of the sequence is 99 terms before the 100th term, so the first term is the 100th term minus 99 times the common difference: 213-99(2) = 213-198 = 15.<br>
Then the next two terms are found by adding 2....<br>
ANSWERS: a(1)=15; a(2) = 17; a(3) = 19