Question

Write any one A.P with common difference - 6 . Find its n ^ (th) term and the sum of the first n terms.​

Answer 1

Answer:

Find some of the terms of AP:

Put n=1, we get a

1

=−1= first term

Put n=2, we get a

2

=−7= second term

Common difference=d=a

2

−a

1

=−7−(−1)=−6

Sum of first n terms:

S

n

=n/2[2a+(n−1)d]

=n/2[−2+(n−1)(−6)]

=n(2−3n)

Sum of first 20 terms:

S

20

=20/2[2(−1)+(20−1)(−6)]

=10[−2−114]

=−1160

Sum of its first 20 terms of AP is −1160.

Answer 2

A≈2400cm

Hope it's correct thank you ♥