ANNOUNCEMENTS
MTH 251 — Fall 2008

12/13/08

We have finished grading the exams. I hope to submit course grades this afternoon, but I suspect that they still won't show up on Online Services until Monday.

12/11/08

Below are the answers to the final. Full solutions can be seen in my office.

1. 18 (cos²(3θ)−sin²(3θ))

2. y=−3x/4+25/4

3. max: 5/4 (θ=2π/3), min: −1 (θ=0)

4. max: 4/(25e²) (u=−2/5), min: 0 (u=0)

5. (a) False (b) False (c) True (d) False

6. (a) one good example is y=x² (b) not possible

7. (a) (0,3) and (6,8) (b) max at x=3, min at x=6 (c) (1,2.25) and (4.75,7.25) (d) x=1,2.25,4.75,7.25

8. (a) 31 cm of rain by 10 AM (b) rain falling at 0.4 cm/hr at 10 AM (c) 4 PM is when 5 cm of rain have fallen (d) when 5 cm of rain have fallen, it will take roughly 2 hours for another cm of rain to fall

9. $49/pound

10. (a) 30π m²/min (b) 1/37500 m/min

12/10/08

Grades will be submitted to the registrar as soon as possible, most likely Saturday night, and should be available through OSU Online Services no later than Monday.

To find out how you did on the final, your best bet is to email your TA, with a copy to me; we will try to respond in a timely fashion. To get your exam or discuss the results, contact your TA.

12/5/08

The following office hours during finals week are open to all students in any section of MTH 251.

Office hours during finals week
Mo 9–11 AM	Steve Scarborough	Kidder 268
Mo 11 AM–1 PM	Yayoi Kurose	Kidder 354
Mo 2–4 PM	Tevian Dray	Kidder 298A
Tu 10:30 AM–12:30 PM	Scott Peterson	Kidder 108B
Tu 1–2 PM	Carolyn McCaffrey	Kidder 338
Tu 2–4 PM	Shari Ultman	Kidder 338

12/3/08

There will be a midterm review session from 4–6 PM on Sunday, 12/7, in Kidder 364.

I will hold extra office hours from 1–3 PM on Friday, 12/5, in Kidder 298A.

12/2/08

The final will be Wednesday, 12/10/08, from 4–5:50 PM in Milam 026.

• The final will be slightly less than twice as long as the midterms.
• Roughly 50% of the final will cover new material.
• The remainder of the final will consist of questions which could have been on one of the midterms.
• We covered most of §1–§4 of the text.
  We did not cover §1.7–§1.8, §2.6, §3.8–§3.10, §4.4, or §4.7–§4.8.
• A list of the most important derivative rules (written using differentials) can be found here.
• You may bring three 3″×5″ index cards (both sides) of handwritten notes.
  Equivalently, you may use one 8½″×11″ piece of paper (one side).
• Other rules and suggestions for the final are the same as for the first midterm.
• Friday's class will be devoted to review. Come prepared to ask questions!

12/1/08

Today's slides can be found here.

11/25/08

The optional makeup skills test will be offered on the following days:

Tuesday, 12/2/08, at 6 PM in Gilbert 124;

Thursday, 12/4/08, at 7 PM in Gilbert 124.

• You may take both makeup tests, but only at the locations and times listed above.
• If you have an unavoidable conflict with both makeup times, talk to me about scheduling options.
• You must show your OSU ID in order to take the makeup skills test.

11/20/08

Some comments about next week's HW assignment.

• Only the first page (problems 1 and 2) of Lab 8 are assigned.
• Simple paths are sufficient: start off horizontally on the road just outside the hills, then at some point head straight through the hills.
• You don't need to go around the hills in the picture …

11/18/08

Instead of a lab, there will be a skills test this week in recitation.

• The skills test is completely closed book; no notes, no calculators.
• Expect 10 problems comparable to those from last week's lab (Lab 7).
• No partial credit will be given!
• You do not need to simplify your answers.
• A score of 8/10 or better will be recorded as 100%.
• A score of 7/10 will be recorded as 50%.
• A score of 6/10 or lower will be recorded as 0%.
• There will be an opportunity to retake the test outside of class (most likely on Tu eve 12/2/08).

11/17/08

Shari's Wednesday office hour this week will be at 12 PM (instead of 1 PM) in Kidder 338.

Her MLC hour that day at 11 AM is unaffected.

11/12/08

Midterms will be handed back on Thursday; the curve will be announced on Friday.

I will again hold extra office hours from 1–3 PM on Friday, 11/14, in Kidder 298A.
Priority will be given to those who wish to discuss their standing in the course.

Friday is the last day to withdraw.

11/11/08

Below are the answers to the second midterm. Full solutions can be seen in my office.

Version a

1. (a) F (b) F

2. y=6x−9

3. No

4. sin(3θ)/3

Version b

1. y=12x−16

2. No

3. sin(5θ)/5

4. (a) F (b) F

Both versions

5. 3w²/(1+w⁶)

6. −1

7. (a) positive (b) positive (c) increasing (d) decreasing

8. −1<x<0

(Many other answers to Problem 7 are possible, so long as the answers to (b) and (c) match, and your graph matches your other answers.)

11/7/08

Problem 68 of §3.4 is not clearly worded, and can be safely omitted.

The intent of the problem is to ask for the derivatives of the given functions with respect to x.

11/5/08

The example of implicit differentiation done at the end of class today is discussed in Examples 1 & 2 of §3.7.

A graph of this equation is shown in Figure 3.34.

11/4/08

There will be a midterm review session from 2–4 PM on Sunday, 11/9, in Kidder 350.

I will hold extra office hours from 1–3 PM on Friday, 11/7, in Kidder 298A.

11/3/08

This week only, Shari's Wednesday office hour will be at 12 PM (instead of 1 PM) in Kidder 338.

Her MLC hour that day at 11 AM is unaffected.

11/1/08

The second midterm will be Monday 11/10/08 in class.

• The second midterm covers most of Chapter 3 of the text.
  We will not cover sections §3.8–§3.10, but it wouldn't hurt to skim the first part (only) of §3.9.
• You may bring two 3″×5″ index cards (both sides) of handwritten notes.
• Other rules and suggestions for this midterm are the same as for the first midterm.
• Friday's class will be devoted to review. Come prepared to ask questions!

10/26/08

Some WeBWorK problems for Chapter 3 have been posted.

• See below for the original announcement about using WeBWorK.
• The problems for Chapter 3 include many drill questions, and are therefore a good way to practice both derivative and algebra skills.
• Additional problems for the later sections of Chapter 3 will be posted next week without further announcement.

10/23/08

Below are the answers to the first midterm. Full solutions can be seen in my office.

1. (a) T (b) T (c) F (d) T (e) T

2. (a) h(x)=37−3x (b) g(x)=16(3/2)^x

3. (a) 25/4 ft/s² (b) 5/2 ft/s²

4. −2

5. d

6. b

7. (a) 400 cans by age 14. (b) 50th can at age 6. (c) 50 cans per year at age 12. (d) 1 week per can after 450 cans. (See full solution for better wording.)

10/22/08

You may want to read, or at least skim, §2.5 prior to tomorrow's recitation — and perhaps prior to attempting this week's homework. This (fairly easy) material has not yet been covered in class...

10/20/08

There is a (short) homework assignment this week.

10/17/08

A good example of how to interpret derivatives, similar to the one we did at the end of class today, is Example 5 at the end of §2.4.

10/16/08

There will be a midterm review session from 4–6 PM on Sunday, 10/19, in Kidder 350.

There will also be an extra office hour from 11 AM–12:30 PM on Friday, 10/17, in Kidder 338.

10/15/08

As mentioned in class today, you might want to try to determine the derivative of x^x at x=2.

To 5 significant figures, the answer is 6.7726.

A few good questions on interpreting derivatives are available here.

10/11/08

The first midterm will be Monday 10/20/08 in class.

• The first midterm covers Chapter 1 and most of Chapter 2 of the text.
  We didn't emphasize §1.7–§1.8; you may skip these sections, but it wouldn't hurt to skim them.
  We may not get to §2.5 this week, and we will not cover §2.6; these sections will not be on the exam.
• The Exercises at the end of each section in MHG are an excellent skills check, and the Check your Understanding questions at the end of each chapter are an excellent review.
• The exam is closed book; calculators may be used.
• You may bring a 3″×5″ index card (both sides) of handwritten notes.
• Please write your exams in pencil or black ink (blue ink is OK).
• Friday's class will be devoted to review. Come prepared to ask questions!

10/8/08

The figure shown in class which summarizes the geometry of trig can be found here.

10/6/08

The doubling time for the population growth problem discussed in class today (§1.4:32) is 20.6 years.

10/3/08

Graphs of exponential functions, some of which were shown in class, can be found here.

10/2/08

I will be in my office tomorrow (Friday) from 10–11:45. Regular office hours, as indicated on the course home page, will resume next week.

9/20/08

In addition to the assigned and recommended homework, some further practice problems are available online through WeBWorK. These problems will not be graded.

• Use your ONID userid as both the username and initial password (and then change the password).
• Try at least part of the Orientation to get started.
• Some online help is available here.

This system is being tried on an experimental basis, with the long-term goal of possibly being used for graded homework in the future.

Please be patient with glitches, and please don't hesitate to send me comments or questions.

9/1/08

The math department offers some general advice on calculators here, which may however be slightly out of date. Most students find a graphing calculator to be helpful for some of the homework and lab problems in MTH 251, although (almost) all of the problems can in fact be done without one.

Graphing calculators will be allowed on exams (but not on the skills test), but should not be necessary.

8/31/08

Explore the course website. In particular, make sure you understand the grading policy, and be sure to find the homework assignments.

Although you can access the website from within Blackboard, it is not a true Blackboard site. In particular, announcements can only be read by following the link on the course homepage; they will not show up automatically when logging into Blackboard.