Question

2,3,1,-2,-3, ....

The first five terms of a sequence are shown above. After the second term, each term in the sequence is the difference of the two terms that precede it. For example, the third term can be obtained by subtracting the first term from the second term. What is the sum of the first 20 terms of the sequence.

Answer 1

The sum of the fust 20 terms in the sequence is 5 because williamwu309 said so

Answer 2

Well, the best way to solve this is maybe just to find a pattern, so 2, 3, 1, -2, -3, -1, 2, 3, 1, -2, -3, -1, so we find out that it repeats and the sum is 0 every 6 terms! Now that we know this, We can just find out the last two digits, which are 2 and 3. So
`2 + 3 =`5, which is our answer