Question

if the nth term of an AP is 5n-2 and sum of first 3 term is​

Answer 1

Step-by-step explanation:

formula for nth term of A.P is

an= a+(n-1)d

5n-2=a-d+nd

comparing coefficient

d=5

a-d=-2

a=3

now sum of first 3 terms= 3+5+7 = 15

or you can do by formula

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