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Arithmetic sequences and sums

Arithmetic sequences and sums

From the course: Test Prep: GRE

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Arithmetic sequences and sums

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- [Voiceover] Sometimes you're going to get a problem with an arithmetic sequence. So an arithmetic sequence is a sequence of numbers that all have the same difference between them. So an example of that would be like one, two, three, four. Another example would be two, four, six, eight. There's a common difference between each of the numbers in these two lists. This one, the common difference is two; this one, the common difference is one. So we would call those arithmetic sequences. So sometimes it's handy to know a formula to get the sum of an arithmetic sequence. So let's take a look at this problem. The sum of the numbers from 1 to 10 is 55, what is the sum of the integers from 1 to 50? We definitely don't want to sit there and add them all up. That's going to take a while. So there's a formula, and I'll write it down first here for us, the sum of an arithmetic sequence. So let me explain. N is the number that you're counting up to in the sequence, the term, I should say, that…

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