Exercise 9.
Generalize Exercise 2.3.8: Find a closed formula for the sequence of differences of \(a_n = an^2 + bn + c\text{.}\) That is, prove that every quadratic sequence has arithmetic differences.
Generalize Exercise 2.3.8: Find a closed formula for the sequence of differences of \(a_n = an^2 + bn + c\text{.}\) That is, prove that every quadratic sequence has arithmetic differences.