SOLUTION: Instead of drawing out all the rectangles, what is the rule to find the perimeter of a 100th rectangle. The perimeter of 1st rectangle is 6, second rectangle perimeter is 10. Third

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Question 397027: Instead of drawing out all the rectangles, what is the rule to find the perimeter of a 100th rectangle. The perimeter of 1st rectangle is 6, second rectangle perimeter is 10. Third Triangle perimeter is 14. The 5th rectangle perimeter is 18. So, how can I find the perimeter by rule of a 100th rectangle?
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
The sequence of perimeters is arithmetic.
a%5Bn%5D+=+a%5B1%5D+%2B+%28n-1%29d+=+6+%2B+%28n-1%294+=+6+%2B+4n+-+4+=+4n+%2B+2.
Therefore the perimeter of the 100th rectangle is a%5B100%5D+=+4%2A100+%2B+2+=+402.