More Exercises on Matrix Operations and Applications
1. Using Cramer’ s rule , find x3 in the solution
to the following system of equations:
2. Multiply out the quadratic form in variables x 1 and x2 defined by
3. For the matrix
(a) Compute all the principal minors of A. What do these tell you about whether A
is positive or negative definite or semidefinite?
4. Consider a Markov process with two states in which:
• From state 1, an individual moves to state 2 with
probability 3/4 and remains in
state 1 with probability 1/4;
• From state 2, an individual moves to state 1 with
probability 1/2 and remains in
state 2 with probability 1/2.
For this process, do exercises (a) through (c) below:
(a) What is the transition matrix of this process?.
(b) In a large population whose individuals obey these
transition probabilities in
periods t = 1, 2, . . ., suppose that at t = 1 half the population are in state 1 and
half are in state 2. What is the distribution across states at t = 2?
(c) Use eigenvectors to find a stable state of this Markov