Question

In an AP if S= 5, S²= 12 Then value of d is A)-2, B) 1 C)2 D) 3​

Answer 1

Answer:

Correct option is

A

800

Step-by-step explanation:

As we know that the sum of first n terms is given by S

n

=

2

n

(2a+(n−1)d), where a & d are the first term & common difference of an AP.

Since, a=2,d=4,S

20

=?

∴S

20

=

10

20

[2a+(20−1)4]

S

20

=10[4+76]

S

20

=800