The nth term of an AP is (2 n+1) then the sum of the first three terms of A.P. is [[1]].

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The nth term of an AP is (2 n+1) then the sum of the first three terms of A.P. is [[1]].

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answer is 15.

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Detailed Solution

The nth term of an AP is (2 n+1) then the sum of the first three terms of A.P. is 15.
Given that the

n t h

term of an AP is

2 n + 1

.
Putting

n = 1, 2, and 3

to get the first, second, and third terms.
Evaluating the first term,

n 1 = 2 × 1 + 1 n 1 = 2 + 1 n 1 = 3

Evaluating the second term,

n 2 = 2 × 2 + 1 n 2 = 4 + 1 n 2 = 5

Evaluating the third term,

n 3 = 2 × 3 + 1 n 3 = 6 + 1 n 3 = 7

Evaluating the sum of the first terms,

= 3 + 5 + 7 = 15

Therefore, the sum of the first three terms is 15.

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