Since we know the sequence is quadratic, we expect the
-th term to have the general form

Plug in the first 3 known values of the sequence to form a system of equations.



Eliminating
gives


Eliminating
gives

Solving for
, we get


So, the
-th term of the sequence is

Writing equivalent equations help you solve system of equations because it sets it up for being broken down part by part.
Answer:
-3 = x
Step-by-step explanation:
4 (2x + 3) = 4x + 24 + 6x – 6
8x + 12 = 10x + 18
12 = 2x + 18
-6 = 2x
-3 = x