Question

SOO EASY!!! HELP ME WITH THIS QUESTION OF AN

Answer 1

1+4+7..........x = 510

$a = 1$
$d = 3$
$an = a +( n - 1)d$
x = 1 + (n-1)3
$\frac{x - 1}{3} = n - 1$
n =
$\frac{x + 2}{3} = n$

now.
$sn = \ \frac{n}{2}(2a + (n - 1)d$
now use this formula and get your answer

sn=510

a = 1

d = 3

n = x+1/3