M4 · Strategist
Algebra
Sequences
Formula
arithmetic: u_n = a + (n-1)d ; geometric: u_n = a x r^(n-1)
Rule
Arithmetic sequences add a constant, geometric ones multiply by a constant.
Example
5, 8, 11 ... has d = 3 so u_10 = 5 + 9 x 3 = 32
Tip
Find the difference or ratio between consecutive terms first.
Learn this concept
Advanced sequences