Question

For the following sequence determine the common difference (if it is an arithmetic sequence) or the common ratio (if it is a geometric sequence).

-7x + 8, -12x + 12, -17x + 16, . . .

Possible anwers:
-5x + 4
5x + 4
-5x - 4
5x-4

Answer 1

The first one is the answer.

Explanation:

It's an arithmetic sequence. It has a common difference.

d = an - a_n-1

an = -12x + 12

a_n-1 = - 7x + 8

d = -12x + 12 - (-7x + 8)

d = -12x + 12 + 7x - 8

d = -5x + 4

Try it. Let's try for the third term

-12x + 12 - 5x + 4

- 17x + 15 which is exactly what the third term is.