Question

IN AN AIRTHMETIC PROGRESSION ,IF An=2n+3 , THEN FIND THE VAUE OF $S_{3}$

Answer 1

Answer:

21

Step-by-step explanation:

a(n) = 2n + 3

=> First term ( a ) = a(1) = 2 + 3 = 5

=> Last term ( l ) = a(3) = 2(3) + 3 = 6 + 3 = 9

S(n) = n/2 (a + l)

=> S(3) = 3/2 ( 5 + 9 )

=> S(3) = 3/2 × 14

=> S(3) = 3 × 7

=> S(3) = 21

Answer 2

Answer:

21

Step-by-step explanation:

use the general terms method