TOPICS
Search

Binet Forms


The two recursive sequences

U_n=mU_(n-1)+U_(n-2)
(1)
V_n=mV_(n-1)+V_(n-2)
(2)

with U_0=0, U_1=1 and V_0=2, V_1=m, can be solved for the individual U_n and V_n. They are given by

U_n=(alpha^n-beta^n)/Delta
(3)
V_n=alpha^n+beta^n,
(4)

where

Delta=sqrt(m^2+4)
(5)
alpha=(m+Delta)/2
(6)
beta=(m-Delta)/2.
(7)

A useful related identity is

 U_(n-1)+U_(n+1)=V_n.
(8)

Binet's formula is a special case of the Binet form for U_n corresponding to m=1.


See also

Binet's Formula, Fibonacci Q-Matrix, Lucas Sequence

Explore with Wolfram|Alpha

Cite this as:

Weisstein, Eric W. "Binet Forms." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/BinetForms.html

Subject classifications