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What is the sum of the series?
Σ (2k2 – 4)
k=1

asked
User Rodpl
by
7.6k points

1 Answer

3 votes

The sum of the series Σ (2k² - 4) from k = 1 to n can be found using the following formula:

Σ (2k² - 4) = [2(1²) - 4] + [2(2²) - 4] + [2(3²) - 4] + ... + [2(n²) - 4]

= 2(1² + 2² + 3² + ... + n²) - 4n

The sum of squares of the first n natural numbers can be calculated using the formula:

1² + 2² + 3² + ... + n² = [n(n + 1)(2n + 1)] / 6

Substituting this value in the above equation, we get:

Σ (2k² - 4) = 2[(n(n + 1)(2n + 1)) / 6] - 4n

= (n(n + 1)(2n + 1)) / 3 - 4n

Therefore, the sum of the series Σ (2k² - 4) from k = 1 to n is (n(n + 1)(2n + 1)) / 3 - 4n.

answered
User Farid Chowdhury
by
8.3k points

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