Question

if the nth term of an A.P is 2n + 1 find the sum of the first 3 terms of the A.P

Answer 1

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Answer 2

$\sf{\underline{Question -}}$

If the nth term of an A.P is 2n + 1 find the sum of the first 3 terms of the A.P.

$\sf{\underline{Answer -}}$

The sum of first three terms of the A.P is 15.

$\sf{\underline{Explanation -}}$

Given, nth term of an A.P = $\sf{2n+1}$

Then,

First term of A.P = $\sf{2(1)+1}$

⇒ $\sf{2+1}$

⇒ $\sf{3}$

Second term of A.P = $\sf{2(2)+1}$

⇒ $\sf{4+1}$

⇒ $\sf{5}$

Third term of A.P = $\sf{2(3)+1}$

⇒ $\sf{6+1}$

⇒ $\sf{7}$

Sum of first three terms of A.P,

⇒ $\sf{3+5+7}$

⇒ $\sf{15}$