Question

If 3 5 7 9 are in AP. Find the sum of first 20 terms​

Answer 1

Answer:

a = 3

d= 2

n =20

Step-by-step explanation:

s = n/2(2a(n-1 l)d)

s²⁰= 20/2× 2×3(20-1)×2

= 10×6 × 19 ×2

=190×12

=2280 ans

Answer 2

Since the differences of the terms are equal

2nd term - 1st term = 3rd - 2nd

The series is AP

SUM OF 20 terms is solved below