Question

given a=2 d=8 Sn=-14 find n and a n​

Answer 1

Sn=n/2(2a+(n-1)d)

14=n/2(4+(n-1)8)

14=n/2(4+8n-8)

14=n/2(8n-4)

28=n(8n-4)

28=4n(2n-1)

7=2n*n-1

2n*n-8=0

2n*n=8

n*n=4

n=2

an=a+(n-1)d

an=2+(2-1)8

an=10