Math 341: Differential Equations (Fall 2014)

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Quizzes
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Date Assigned Date Due Topic Hint
Quiz 9
Mon Nov 10
Fri Nov 14
Introduction to Laplace Transforms
HINT #1: You basically need to do one step of integration by parts in order to get the formula for L{t^a}. Think about which function in the integral you want to differentiate in order to have t^(a-1) appear.
HINT #2: Try integration by substitution (i.e. u=st) in order to obtain the definition of Gamma[a]

Quiz 8
Mon Nov 3
Wed Nov 5
Bifurcations in Quasi-Linear Systems of ODEsHINT: Notice that you don't have t -> infinity in part (d). Your expression for r(t) in both (c) and (d) should have an unknown constant C in it.

NOTE: the contradiction between part (a) saying the system has  acenter for all values of a when in actuality the nature of the fixed point is very different for different values of a! (i.e. Linearization doesn't work well when the Jacobian has fully complex eigenvalues or a zero eigenvalue)

BONUS Quiz 3
Mon Oct 27
Fri Oct 31
Visualizing Solutions of Linear Systems of ODEs HINT: Also draw in the straight-line solutions. What does existence and uniqueness theorem tell you about crossing these solutions? Our general solution previously discussed applies to zero eigenvalues. What is e^0?. What will a zero eigenvalue due to the solution trajectories?
Quiz 7
Mon Oct 27
Fri Oct 31
Bifurcations in Linear Systems of ODEs HINT: What property of the matrix controls when a linear system of ODEs will change its character?
Quiz 6
Fri Oct 17
Wed Oct 22 Linear Systems of ODEs HINT: Recall how you can check whether an eigenvector is associated with an eigenvalue is if it solves Ax=qx where q is an eigenvalue and x is eigenvector.
BONUS Quiz 2
Fri Sep 26 Mon Sep 29 Review of Chapter 1 Topics
HINT: This is intended to be a quick (15-minute short-answer) quiz.
Quiz 5
Fri Sep 26
Mon Sep 29
Solutions of Linear Differential Equations
HINT: Closed form means that you don't have an integral in the expression. Make sure you fill out the Reality Check to get 1 point!
Quiz 4 Fri Sep 19 Mon Sep 22
Bifurcations Practice When sketching the bifurcation diagram, think about whether there is any value of α which would correspond to zero as an equilibrium value for y*. (That tells you were your bifurcation curve crosses the  horizontal axis in the αy*-plane.)
Quiz 3
Fri Sep 12
Mon Sep 15
Existence and Uniqueness Theorem
Recall that the domain of definition must be a CONTINUOUS interval of the real line that include the location of the initial condition.
Quiz 2
Fri Sep 5 Mon Sep 8
The Logistic Model of Population
The whole point is that you can sketch a solution of the ODE (representing a future under the logistic model) for  a population WITHOUT solving for an explicit solution. Remember your rules for curve sketching from Calc 1!

Quiz 1

Fri Aug 29
Wed Sep 3
Introduction to Differential Equations Think about a second order differential equation and how many unknown constants its solution would have. What does that imply about its family of solutions?

BONUS Quiz 1

Fri Aug 29
Wed Sep 3
Singular Solutions A singular solution to a DE is another solution that does not fit into the family of solutions generated by changing the constant of integration.