Question

Find the sum of the first 8 terms of the sequence.

1, -3, -7, -11, …

Thank you!

Answer 1

Answer:1,-3,-7,-11,-15,-19,-23,-27,-31

Explanation:

You just subtract -4 every time.

Answer 2

-104.

Explanation:

This is an arithmetic sequence with first term 1 and common difference -4.

Sum of n terms = (n/2)[2a1 + (n-1)d] where a1 = the first term and d=common difference.

S(8) = (8/2) ( 2*1 + (8-1)*-4)

= 4 * (2 + 7*-4)

= 4 * (-26)

= -104.