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The sum to n terms of an arithmetic progression is 5n2 +2n. Find the nth term of the series.a.10n - 3b.10n + 5c.5n - 1d.5n - 2

Question

The sum to n terms of an arithmetic progression is 5n2 +2n. Find the nth term of the series.a.10n - 3b.10n + 5c.5n - 1d.5n - 2

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Solution

The sum to n terms of an arithmetic progression is given by the formula Sn = n/2 [2a + (n-1)d], where a is the first term and d is the common difference. However, in this case, we are given Sn = 5n^2 + 2n.

To find the nth term of the series, we need to find the difference between the sum to n terms and the sum to (n-1) terms. This is because the nth term is equal to the sum to n terms minus the sum to (n-1) terms.

So, the nth term, An = Sn - S(n-1).

Substituting the given Sn and S(n-1) into the equation, we get:

An = [5n^2 + 2n] - [5(n-1)^2 + 2(n-1)] = [5n^2 + 2n] - [5n^2 - 10n + 5 + 2n - 2] = [5n^2 + 2n] - [5n^2 - 8n + 3] = 5n^2 + 2n - 5n^2 + 8n - 3 = 10n - 3

So, the nth term of the series is 10n - 3. Therefore, the correct answer is a.10n - 3.

This problem has been solved

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