SOLUTION: 2+4+6....+42

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Question 989971: 2+4+6....+42
Answer by ikleyn(52812) About Me  (Show Source):
You can put this solution on YOUR website!
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Arithmetic progression.
First term is 2.
The common difference is 2.
The number of terms is %2842-2%29%2F2+%2B+1 = 21.

Use the formula for the sum (see the lesson Arithmetic progressions in this site)

S = %28%28a%5B1%5D%2Ba%5Bn%5D%29%2F2%29.n = %28%282+%2B+42%29%2F2%29.21 = 44%2F2.21 = 22*21 = 462.