Question

Find the sums of the following arithmetic sequences. ​

Answer 1

Answer:

The sum of an arithmetic series is given as:

Sn=n2(2a+(n−1)d)

a+(n−1)d.

5−2=8−5=3.

∴

2+(n−1)⋅3=56.

(n−1)⋅3=54.

n=543+1=19.

∴