SOLUTION: 1-An aritmetic sequence has its 5th term equal to 22 and its 15th term equal to 62.Find its 100th term. 2-Find the sum of the first 50 even positive integers.

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Question 739087: 1-An aritmetic sequence has its 5th term equal to 22 and its 15th term equal to 62.Find its 100th term.
2-Find the sum of the first 50 even positive integers.

Answer by reviewermath(1029) About Me  (Show Source):
You can put this solution on YOUR website!
1. The common difference (slope) is equal to %2862+-+22%29%2F%2815+-+5%29+=+4.
The nth term is 4n + k, we solve for k by substituting n = 5 (and equate to 5th term).
4(5) + k = 22 so k = 2.
The nth term is 4n + 2.
The 100th term is 4(100) + 2 = highlight%28402%29.
2. The sum of the first n positive integers is equal to n%28n%2B1%29%2F2 and the sum of the first n even positive integers is n%28n%2B1%29.
Therefore, the sum of the first 50 positive even integers is 50%2851%29+=++highlight%282550%29.