Question

Find the sum of 405 terms of the given series:

5+ (-5) + 5 + (-5) + 5 + (-5) + ________
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Answer 1

Answer:

I think 450 is the answer of this series

Answer 2

Answer: 5

Explanation: 405 terms means the odd number of terms.

In the given series, the pair,  5 + (-5) = 0

For every two terms, the sum is zero, therefore after adding 404 terms (even number of terms), the sum will again be zero.

We also know that every odd-numbered term is 5 while every even-numbered term is -5.

405 is an odd number, therefore 405th term will be +5.

Hence, The sum of 405 terms = sum of 404 terms + 405th term = 0 + 5 = 5