1-2+3-4+5-6+....+71-72+73=?

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вопрос

This type of sequence involves alternately adding and subtracting consecutive numbers. To find the sum of this sequence, we can group the numbers together and simplify each group as follows:

(1-2) + (3-4) + (5-6) + ... + (71-72) + 73
-1 -1 -1 ... -1 + 73

Now, we need to determine how many pairs of numbers from 1-72 there are. Since each pair yields a sum of -1, we have 36 pairs. Therefore, the sum of the sequence is:

36(-1) + 73
-36 + 73
37

Therefore, the sum of the sequence is 37.