# 2019 Spring - MAT 2680 - Reitz

"...how it differs from the rocks"

# Page 2 of 4

By default, the iPhone automatically converts straight quotes like this:  ‘
into smart quotes, like this  .  You need to turn this functionality off in order to enter the prime (straight quote) symbol in WeBWorK.  The short version is:

To turn smart punctuation off, all you have to do is go to Settings > General > Keyboard, and then turn off the “Smart Punctuation” toggle.

More detailed instructions can be found here:

WeBWorK: Assignment  11-Trench-SeriesSolutions  due Tuesday, 4/16/19, at midnight.

OpenLab: None

Hi everyone,

Exam #2 will be returned in class tomorrow.  If you are a member of this OpenLab site, you can find your grade under Dashboard/OpenLab Gradebook.

Regards,
Prof. Reitz

Hi everyone,

WeBWorK assignment 10 is now available – it is due this Tuesday evening at midnight.

Have a good weekend,
Prof. Reitz

Hi everyone,

Due to a number of factors (we one day behind the syllabus, Spring Break and Exam 3 timing, etc), I am making some minor changes to the class calendar – rearranging topics over the next few lectures.  The remaining material in Chapter 5 and Chapter 6 will be put off for a week or so, and tomorrow we will dive into Chapter 7 – Power Series (we’ll spend the next week or so working on this chapter).  See the most current schedule here.  Let me know if you have any questions.

Regards,
Prof. Reitz

Hi everyone,

As you work through WeBWorK #9, you may run into a few instances where it is not obvious what guess to make for the particular solution to the nonhomogeneous equation.  Here are two tips that might help:

### What if the right side has both an exponential and a trig function?

If the right side of your differential equation has form similar to:  $e^{ax} \cos(bx)$

then your guess should have the form:  $Ae^{ax} \sin(bx) + Be^{ax} \cos(bx)$

### What if the right side is a solution to the complementary equation (where the complementary equation has a repeated root)?

If your initial guess:  $Ae^{ax}$ is a solution to the complementary equation, we adjust it by multiplying by $x$: $Axe^{ax}$.

If $Axe^{ax}$ is *also* a solution to the complementary equation (due to a repeated root), adjust it by multiplying by $x$ again:  $Ax^2e^{ax}$.

Let me know if you run into other weird things.  Questions are natural, and welcome!

Prof. Reitz

I have a conflicting commitment in the Math Department.  However, I should be able to be in class a few minutes early if you have questions.

See you in a bit,
Prof. Reitz

WeBWorK: Assignment  9-Nonhomogeneous  due Tuesday, 4/2, at midnight.
NOTE: Because of our exam on 4/2,  assignment 10-Trench-ReductionOfOrder will be due the following Tuesday, 4/9.

OpenLab:  OpenLab #2: Numerical Methods PROJECT is due Thursday, 4/4, by the start of class.

Hi everyone,

The review sheet for Exam #2 (which will take place on Tuesday, April 2nd) is posted on the Exam Reviews page.  Let me know if you have any questions.

Best regards,
Prof. Reitz

WeBWorK: Assignments 7-SecondOrderRepeated,  and 8-SecondOrderComplex` due Tuesday, 3/26, at midnight.

OpenLab: Your Project is due April 4 (Part 1, Example Data, Part 2)

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