Question

If nth term of an A.P. is (2n + 1), what is the sum of its first three terms ?​

Answer 1

$\huge\tt\underline\red{Ans}\underline {w}\underline\purple{er}\underline{-}\orange {: =15}$

꧁Explaination ꧂

${ \bold { \underline{\large{Given : - }}}} \:$

$a_1 = 2n + 1$

We need to find sum of first three terms

Finding first three terms

$a_1$ = 2(1) + 1

= 2 + 1

= 3

$a_2$= 2(2) + 1

= 4 + 17

= 5

$a_3$ = 2(3)+1

= 6 +1

= 7

So,

Sum of first three terms = $a_1$ +$a_2$+ $a_3$

= 3 + 5 + 7

= 15

hope it will help you