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Linear Algebra/Topic: Linear Recurrences/Solutions
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Solutions
Problem 1
Solve each homogeneous linear recurrence relations.
<li>
<li>
<li>
Answer
<li>
We express the relation in matrix form.
The characteristic equation of the matrix
has roots of and .
Any function of the form
satisfies the recurrence.
<li>
This is like the prior part, but simpler.
The matrix expression of the relation is
and the characteristic equation of the matrix
has the single root .
Any function of the form
satisfies this recurrence.
<li>
In matrix form the relation
gives this characteristic equation.
Problem 2exer:SolvePartRecurSoltn
Give a formula for the relations of the prior exercise, with
these initial conditions.
<li> ,
<li> ,
<li> , , .
Problem 3exer:SeqToRnLinMap
Check that the isomorphism given between and is a linear map.
It is argued above that this map is one-to-one.
What is its inverse?
Problem 4exer:CharEqnIsDeter
Show that the characteristic equation of the matrix is as stated, that is,
is the polynomial associated with the relation.
(Hint: expanding down the final column, and using induction will work.)
Problem 5exer:SoltnsLinRecur
Given a homogeneous linear recurrence relation
, let , ..., be the
roots of the associated polynomial.
<li> Prove that each function
satisfies the recurrence (without initial conditions).
<li> Prove that no is .
<li> Prove that the set
is linearly independent.
Problem 6
(This refers to the value
given in the computer code below.)
Transferring one disk per second, how many years would it take
the priests at the Tower of Hanoi to finish the job?