Question

find the
sum of AP
of first
25 terms of A.P
3,6,9,12,15​

Answer 1

Answer:

Hope this answer helpful for you.

Answer 2

Answer:

975

Step-by-step explanation:

a (first term)= 3

n (total no. of terms)= 25

d (common difference) = 6-3 = 3

an= a+(n-1)d

a25 = 3+(25-1)×3= 3+24×3 = 3+ 72 =75

Sn = n (a+an) ÷2 = 25(3+75) ÷2 = 25 ×78 ÷2 = 25×39 = 975