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the fourth term of an arithmetic sequence is 141, and the seventh term is 132. what is the first term?

User Super
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1 Answer

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The 1st, 4th, and 7th terms make an arithmetic sequence of their own. The 4th term is the average of the 1st and 7th, so ...
(1st +7th)/2 = 4th
1st + 7th = 2×4th
1st = 2×4th - 7th

The first term is ...
2*141 - 132 = 150
User Jackiszhp
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