Question

.Find the sum of frst 20 terms of A.P. 3s 7s 11s 15.... using the formula.​

Answer 1

Step-by-step explanation:

answer of this question

Answer 2

ANSWER:

= 820

step by step explanation :

a = 3

d = a2 -a1

d = 7 - 3

= 4

sn = n/2 ( 2a +( n-1) d)

s2o = 20/2 ( 2/3 ) +(20-1) (4)

= 10 ( 6 + 19 ×4 )

= 10 ( 6+ 76)

= 10 ( 82 )

= 820

hope this helps u........♡♡