Quadratic sequences  Sequences and Series
Quadratic sequences
Lessons
Notes:
The nth term of a quadratic sequence is always in the form
$an^{2}+bn+c$
Second common difference (2nd difference): the common difference of the common difference.
To find the nth term of the quadratic sequence, we need to find the values of a,b, and c. We find them using the three following formulas:
$a = \frac{(2^{nd} difference)}{2}$
$3a+b=2^{nd} term1^{st} term$
$a+b+c=1^{st} term$
Isolate to solve for a,b and c and plug those values into the quadratic sequence. Then you will have the nth term!

Intro Lesson
Quadratic Sequences Overview:

1.
Identifying the a,b,c's
The nth term of a quadratic sequence is always in the form:
$an^{2}+bn+c$
For each following quadratic expressions, find the values of a, b, c. Then list the first three terms of the sequence: