Question

If the sum to the first n terms of an AP is given by S = n(n + 1), find the 20th term of the AP.

Answer 1

Answer:

Step-by-step explanation:

when n=1 then,

s=2

a=2

when n=2

s=6

d=6-2=4

∴ a=2 and d=4

a20= a+19d=2+76=78