Question

List the first ten terms of a sequence whose first term is -10 and whose common difference is -2.

Answer 1

Let a(0) represent the first term; its value is -10.  The next term is found by subtracting 2 from -10, obtaining -12.  Each new term is created by subtracting 2 from the previous one.  Thus, the formula for the nth term is

a(n) = a(0)-2(n-1), or a(n) = -10-2(n-1).

First term:  -10

Second:  -12

Third:  -14,

....

Tenth term:  a(10) = -10-2(10-1) = -10 - 18 = -28