Arithmetic sequence

Question

What is the 15th term of the arithmetic sequence given by the explicit rule a n=-72+(n-1)(16)?

Answer 1

n = -72 + 16n - 16 = 16n - 88

n f(n)

1 -72

2 -56

3 -40

4 -24

So it is an arithmetic sequence with common difference 16=D

The first term is -72=A1

15th term is

A1 + (k-1) * D where k=15

-72 + 14 * 16 = 152