Question

Determine if the sequence below is arithmetic or geometric and determine the

common difference / ratio in simplest form.
12, 7, 2, ...
This is
sequence and the
- is equal to

Answer 1

Answer: First we consider if it is AP by subtracting the 1st term from the 2nd term to find the common difference after which you add the common difference to the 2nd term to find out if it gives you the 3rd term which is 2. Now we go

a = 12 , the. d = 7 - 12 = -5

Now d = -5 , from the second statement above, we add -5 to 7 the 2nd term to find out if it gives 2

7 + (-5)

= 7 - 5

= 2 which is the 3rd term.
Therefore, from the proof above it could be established that the sequence above is an AP. The 2nd part of the question. The common difference is

d = 7 - 12

=. -5 or better still

3rd term minus the 2nd term

2 - 7

= -5

Explanation: