Question

find the sum of first 30 term of an ap is 1 + 5 + 9 +.....​

Answer 1

a=1

d=5-1=4

n=30

$n(30) = 1 + (30 - 1)4 =11 7 \\ s(30) = \frac{30(1 + 117)}{2} = 1770$