Question

The third term in an arithmetic sequence is 10 and the fifth term is 26.If the first term is a1,which is an equation for the nth of this sequence?
please help idk how to do this.
A) an=8n+10
B)an=8n-14
C)an=16n+10
D)16n-38

Answer 1

Just plug in 3 for n and then 5 for n to see if an turns out to be 10 and 26.

n=3:
A) an = 8*3+10 = 34
B) an = 8*3 - 14 = 10  OK
C) an = 16*3+10 = 58
D) an = 16*3 - 38 = 10 OK

n=5:
B) an = 8*5-14 = 26 OK
D) an = 16*5 - 38 = 42

So the answer is B