Math 341: Differential Equations (Fall 2008)
Home > Assignments> Quizzes
Quizzes
Click on the Quiz # to see the solution.
 

#

Date Assigned Date Due Topic Hint

Quiz 1

Fri Sep 5 Mon Sep 8 Introduction to Differential Equations Think about the particular solutions in u variables, what would the initial conditions be then?

Reading Quiz 1

Mon Sep 8 Mon Sep 8 Sections 1.1-1.4    

BONUS Quiz 1

Wed Sep 10 Fri Sep 12 Singular Solutions  What graphical features do you notice about the singular solution y=0 and the family of solutions y=((x+C)^12)/16 to the ODE y'=x sqrt(y)?

 Quiz 2

Fri Sep 12 Mon Sep 15 Analyzing The Logistic Equation Think about what ideas from Calculus you can draw upon to sketch a curve y=f(t) accurately.

BONUS Quiz 2

Wed Sep 17 Fri Sep 19 Bifurcations Recall the quadratic formula for ax^2+bx+c and how to solve quadratic inequalities, i.e. if |x|<2 that means that -2 < x < 2. What must be true at a stable equilibrium point of y'=f(y)?

Reading Quiz 2

Mon Sep 22 Mon Sep 22 Sections 1.5-1.9   

Quiz 3

Fri Sep 26 Mon Sep 29 Systems of ODEs Use your experience with seeing phase portraits of Lotka-Volterra in class to help you draw the pictures in the quiz. Remember properties of logs! log(a)+log(B)=log(AB) and log(e^B)=B.

Reading Quiz 3

Mon Sep 29 Mon Sep 29 Sections 2.1-2.3   

Quiz 4

Fri Oct 10 Wed Oct 15 Visualizing 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?

BONUS Quiz 3

Fri Oct 17 Mon Oct 20 More Practice with Linear Systems of ODEs Although the question does not explicitly ask you to, you should  find the eigenvalues and eigenvectors of the associated matrix. You can use their signs to determine the stability of the origin and thus the trajectories of the given solutions.

Reading Quiz 4

Fri Oct 24 Fri Oct 24 Sections 3.1- 3.6  

Quiz 5

Fri Oct 24 Mon Oct 27 Linear Systems of ODEs and Bifurcation HINT: What property of the matrix controls when a linear system of ODEs will change its character?

Quiz 6

Fri Oct 31 Mon Nov 3 Bifurcation in Quasi-Linear Systems HINT: Why can't t -> infinity in part (d)? Your expression for r(t) in both (c) and (d) should have an unknown constant C in it.

Quiz 7

Wed Nov 12 Mon Nov 17 Laplace Transforms HINT: 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 in order to obtain the definition of Gamma[a].

Reading Quiz 5

Fri Nov 21 Fri Nov 21 Sections 6.1-6.5.  

Quiz 8

Mon Nov 24 Mon Dec 1 Inverse Laplace Transforms HINT: Notice the difference in where the two sums start. Also, note that anything that doesn't have a k in it does not need to be to the right of the summation symbol. The graphs of b(t) and f(t)=a(t)-b(t) should be especially pretty. :)

BONUS Quiz 4

Mon Nov 24 Mon Dec 1 Convolution HINT:  L(f*f)=F*F=F^2. To find F will involve taking a square root which leads to the plus/minus symbol.