Question

PLEASE EXPLAIN

A theater has 35 seats in the first row. Each row has four more seats than the row before it. Which expression represents the number of seats in the nth row?

1) 35+(n+4)
2) 35+(4n)
3) 35+(n+1)(4)
4) 35+(n-1)(4)

Answer 1

This is an arithmetic sequence because each term is a constant difference from the previous term, called the common difference.  Any arithmetic sequence can be expressed as:

a(n)=a+d(n-1), a=initial term, d=common difference, n=term number.

In this case a=35 and d=4 so

a(n)=35+4(n-1)  It's answer 4)