Quadratic Sequences (Junior Cert Mathematics): Flashcards

Second differences are constant

Differences between consecutive terms

Differences between the first differences

$T_n = an^2 + bn + c$

The term you're trying to find

Position of term in sequence

$2a$ equals the second difference

$a$ is half the second difference

Find the second difference

Use first two terms to create two equations

$a = 1$

$T_n = n^2 + 3$