Question

2, 6, 10, 14,... upto 20 terms,Find the sum of the first n terms of the following AP.as asked for.

Answer 1

a=2
d=6-2=4
n=20
s=n/2[2a+(n-1).d]
s=20/2[2.2+(20-1).4]
s=10[4+(19).4]
s=10[4+76]
s=10[80]
s=10*80
s=800
is my ans is correct or not

Answer 2

a = 2

d = 6 - 2 = 4

Sn = n/2 [ 2a + (n-1) d]

= 20/2 [ 2(2) + 19(4)]

= 10 ( 4 + 76)

= 10 × 80

= 800