What are the measures of an interior angle and an exterior angle of a regular 30-gon?
1 answer:
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Problem 1)
The notation you wrote down is a bit odd. There seems to be a typo. Please double check.
Assuming you meant to write
then the answer is choice D) 2, 6, 18, 54, 162, ...
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Why is this? Because each term is found by multiplying the previous term by 3
first term = 2
second term = (first term)*3 = 2*3 = 6
third term = (second term)*3 = 6*3 = 18
fourth term = (third term)*3 = 18*3 = 54
fifth term = (fourth term)*3 = 54*3 = 162
this pattern continues forever
Extra information: The closed form equation is where 2 is the first term, 3 is the common ratio, and n is a positive integer.
some more info: notice picking any term in sequence {2,6,18,54,162,...} and dividing it over its previous term leads to 3
6/2 = 3
18/6 = 3
54/18 = 3
162/54 = 3
None of the other sequences listed have this property of the adjacent terms dividing to a constant ratio. So none of the other sequences are geometric.
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Problem 2)
The first term is (ie, the first term is 2)
The recursive definition is basically telling us "to get the next term, raise the prior term as an exponent with 3 as the base"
The general template looking like this: nth term = 3^(term just before the nth term)
The first term is 2, so the next term must be 3^2 = 9
The third term would be 3^9 = 19683 and so on.
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<h3>Final Answer: choice B) 9</h3>