Question

8,12,6 is an ap find s20 and s35 using the formula sn=n/2[2a + (n-1)d]

Answer 1

Step-by-step explanation:

Solution:

Given a=6d=3

S

27

=

2

n

[2a+(n−1)d]

S

27

=

2

27

[2×6+26×3]

=

2

27

[12+78]

=

2

27

[90]

=1,215