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Question 29354: Use the arithmetic sequence of numbers 2,4,6,8,10... to find the following:
1. 
2. Using the formula for the Nth term of an arithmetic sequence, what is 101st term?
3. Using the formula for the sum of an arithmetic series, what is the sum of the first 20 terms?
Answer by longjonsilver(2297)   (Show Source):
You can put this solution on YOUR website! 1. well waht is the difference between 2 and 4? or between 6 and 8? Answer is 2.
2.
1st term is a --> which is 2, from the question
2nd term is a+d
3rd term is a+2d
4th term is a+3d
5th term is a+4d
6th term is a+5d
7th term is a+6d
so, in general, looking at the pattern,
nth term is a+(n-1)d
So, when n=101, the 101st term is a+100d
--> 2+100*2
--> 2+200
--> 202
Sum of first n terms is (from memory) 
so, n=20, a=2 and d=2...put them in and work out the answer. Answer is 400.
jon.
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