course phy 121

??????????S??assignment #001001. Only assignment: prelim asst

qa prelim

??????€???V??v

assignment #001

qa prelim

qa prelim

......!!!!!!!!...................................

11:45:08

`q001. Part 1 includes six activities. If you have completed an activity, just enter the answer 'completed'.

This question is appearing in the Question box. The box to the right is the Answer box, where you will type in your answers to the questions posed here.

To use this program you read a question, then enter your answer in the Answer box and click on Enter Answer. In your answers give what is requested, but don't go into excruciating detail. Try to give just enough that the instructor can tell that you understand an item.

After entering an answer click on Next Question/Answer above the Question box.

Do you understand these instructions?

......!!!!!!!!...................................

RESPONSE -->

I understand

.................................................

......!!!!!!!!...................................

11:47:44

This program has created the folder c:\vhmthphy on your hard drive.

Browse to that folder and locate the file whose name begins with SEND. The name of this file will also include your name, as you gave it to the program, and the file will show as a Text file.

Never tamper with a SEND file in any way. It contains internal codes as if these codes are tampered with you won't get credit for the assignment. However you are welcome to copy this file to another location and view it, make changes, etc. Just be sure that when requested to do so you send the instructor the original, tamper-free file.

State in the Answer box whether or not you have been able to locate the SEND file. Don't send the SEND file yet. Note that more questions/instructions remain in the q_a_prelim.

......!!!!!!!!...................................

RESPONSE -->

I found the send file.

.................................................

......!!!!!!!!...................................

11:50:24

`q002. Note that every time you click on Enter Answer the program writes your response to your SEND file. Even if the program disappears all the information you have entered with the Enter Answer button will remain in that file. This program never 'unwrites' anything. Even if this program crashes your information will still be there in the SEND file. Explain this in your own words.

......!!!!!!!!...................................

RESPONSE -->

Every time I submit an answer it will be saved to the send file. No matter what happens this file will never be deleted.

.................................................

......!!!!!!!!...................................

11:51:38

Any time the instructor does not post a response to your access site by the end of the following day, you should resubmit your work using the Submit Work form, and be sure at the beginning to indicate that you are resubmitting, and also indicate the date on which you originally submitted your work.

If you don't know where your access site is or how to access it, go to

http://www.vhcc.edu/dsmith/_vti_bin/shtml.dll/request_access_code.htm and request one now. You can submit the q_a_prelim without your access code, but other assignments should contain your code.

......!!!!!!!!...................................

RESPONSE -->

I have already requested an access code but I don't have it yet.

.................................................

......!!!!!!!!...................................

11:52:08

`q003. If you are working on a VHCC computer, it is probably set up in such a way as to return to its original configuration when it is rebooted. To avoid losing information it is suggested that you back up your work frequently, either by emailing yourself a copy or by using a key drive or other device. This is a good idea on any computer. Please indicate your understanding of this suggestion.

......!!!!!!!!...................................

RESPONSE -->

I will back up my work.

.................................................

???i?????\??????assignment #001

001. typewriter notation

qa initial problems

01-17-2009

......!!!!!!!!...................................

12:59:49

`q001. Explain the difference between x - 2 / x + 4 and (x - 2) / (x + 4). The evaluate each expression for x = 2.

......!!!!!!!!...................................

RESPONSE -->

In the second equation you are instructed to do the subtraction and the addition first because of the paranthesis.

confidence assessment: 1

.................................................

......!!!!!!!!...................................

13:08:52

2 ^ x + 4 indicates that you are to raise 2 to the x power before adding the 4.

2 ^ (x + 4) indicates that you are to first evaluate x + 4, then raise 2 to this power.

If x = 2, then

2 ^ x + 4 = 2 ^ 2 + 4 = 2 * 2 + 4 = 4 + 4 = 8.

and

2 ^ (x + 4) = 2 ^ (2 + 4) = 2 ^ 6 = 2*2*2*2*2*2 = 64.

......!!!!!!!!...................................

RESPONSE -->

In the second equation you have to do what is in the paranthesis first.

2^x+4 = 2^2+4 = 4+4 = 8

2^(x+4) = 2^ (2+4) = 2^ 6= 64

self critique assessment: 3

.................................................

......!!!!!!!!...................................

13:30:40

`q003. What is the numerator of the fraction in the expression x - 3 / [ (2x-5)^2 * 3x + 1 ] - 2 + 7x? What is the denominator? What do you get when you evaluate the expression for x = 2?

......!!!!!!!!...................................

RESPONSE -->

The numerator is x-3 and the denominator is [(2x-5)^2 * 3x + 1 ].

2 - 3 / [ (2*2-5)^2 * 3*2 + 1 ] - 2 + 7*2

2-3/ [ (4-5)^2*6+1] -2+14

2-3 / [(-1) ^2 * 6+1] -2+14

2-3 / [1*6+1] -2+14

2-3 / [6+1] -2+14

2-3/ 7-2+14

-1/7 -16

-1/7-112/7

-113/7

confidence assessment: 2

.................................................

......!!!!!!!!...................................

13:33:49

The numerator is 3. x isn't part of the fraction. / indicates division, which must always precede subtraction. Only the 3 is divided by [ (2x-5)^2 * 3x + 1 ] and only [ (2x-5)^2 * 3x + 1 ] divides 3.

If we mean (x - 3) / [ (2x-5)^2 * 3x + 1 ] - 2 + 7x we have to write it that way.

The preceding comments show that the denominator is [ (2x-5)^2 * 3x + 1 ]

Evaluating the expression for x = 2:

- 3 / [ (2 * 2 - 5)^2 * 3(2) + 1 ] - 2 + 7*2 =

2 - 3 / [ (4 - 5)^2 * 6 + 1 ] - 2 + 14 = evaluate in parenthese; do multiplications outside parentheses

2 - 3 / [ (-1)^2 * 6 + 1 ] -2 + 14 = add inside parentheses

2 - 3 / [ 1 * 6 + 1 ] - 2 + 14 = exponentiate in bracketed term;

2 - 3 / 7 - 2 + 14 = evaluate in brackets

13 4/7 or 95/7 or about 13.57 add and subtract in order.

The details of the calculation 2 - 3 / 7 - 2 + 14:

Since multiplication precedes addition or subtraction the 3/7 must be done first, making 3/7 a fraction. Changing the order of the terms we have

2 - 2 + 14 - 3 / 7 = 14 - 3/7 = 98/7 - 3/7 = 95/7.

COMMON STUDENT QUESTION: ok, I dont understand why x isnt part of the fraction? And I dont understand why only the brackets are divided by 3..why not the rest of the equation?

INSTRUCTOR RESPONSE: Different situations give us different algebraic expressions; the situation dictates the form of the expression.

If the above expression was was written otherwise it would be a completely different expression and most likely give you a different result when you substitute.

If we intended the numerator to be x - 3 then the expression would be written (x - 3) / [(2x-5)^2 * 3x + 1 ] - 2 + 7x, with the x - 3 grouped.

If we intended the numerator to be the entire expression after the / the expression would be written x - 3 / [(2x-5)^2 * 3x + 1 - 2 + 7x ].

......!!!!!!!!...................................

RESPONSE -->

I assumed that x was part of the fraction. But I understand why I messed up.

self critique assessment: 2

.................................................

......!!!!!!!!...................................

13:45:24

`q004. Explain, step by step, how you evaluate the expression (x - 5) ^ 2x-1 + 3 / x-2 for x = 4.

......!!!!!!!!...................................

RESPONSE -->

(x - 5) ^ 2x-1 + 3 / x-2

(4-5) ^ 2(4) -1 +3 / 4 -2

-1 ^ 8 - 1 + 3 / 4-2

1 -1 + 3 / 4 -2

1 -1 + .75 -2

.75-2

-1.25

confidence assessment: 1

.................................................

......!!!!!!!!...................................

13:47:43

We get

(4-5)^2 * 4 - 1 + 3 / 1 - 4

= (-1)^2 * 4 - 1 + 3 / 4 - 2 evaluating the term in parentheses

= 1 * 4 - 1 + 3 / 4 - 2 exponentiating (2 is the exponent, which is applied to -1 rather than multiplying the 2 by 4

= 4 - 1 + 3/4 - 2 noting that 3/4 is a fraction and adding and subtracting in order we get

= 1 3/4 = 7 /4 (Note that we could group the expression as 4 - 1 - 2 + 3/4 = 1 + 3/4 = 1 3/4 = 7/4).

COMMON ERROR:

(4 - 5) ^ 2*4 - 1 + 3 / 4 - 2 = -1 ^ 2*4 - 1 + 3 / 4-2 = -1 ^ 8 -1 + 3 / 4 - 2.

INSTRUCTOR COMMENTS:

There are two errors here. In the second step you can't multiply 2 * 4 because you have (-1)^2, which must be done first.?Exponentiation precedes multiplication. ?

Also it isn't quite correct to write -1^2*4 at the beginning of the second step. If you were supposed to multiply 2 * 4 the expression would be (-1)^(2 * 4).?

Note also that the -1 needs to be grouped because the entire expression (-1) is taken to the power.?-1^8 would be -1 because you would raise 1 to the power 8 before applying the - sign, which is effectively a multiplication by -1.?......!!!!!!!!...................................

RESPONSE -->

self critique assessment: 0

&#Your response did not agree with the given solution in all details, and you should therefore have addressed the discrepancy with a full self-critique, detailing the discrepancy and demonstrating exactly what you do and do not understand about the given solution, and if necessary asking specific questions (to which I will respond).

&#

.................................................

......!!!!!!!!...................................

13:48:40

*&*& Standard mathematics notation is easier to see. On the other hand it's very important to understand order of operations, and students do get used to this way of doing it.

You should of course write everything out in standard notation when you work it on paper.

It is likely that you will at some point use a computer algebra system, and when you do you will have to enter expressions through a typewriter, so it is well worth the trouble to get used to this notation.

Indicate your understanding of the necessity to understand this notation.

......!!!!!!!!...................................

RESPONSE -->

I understand it is important to understand this notation

self critique assessment: 2

.................................................

......!!!!!!!!...................................

13:56:35

`q005. At the link

http://www.vhcc.edu/dsmith/genInfo/introductory problems/typewriter_notation_examples_with_links.htm

(copy this path into the Address box of your Internet browser; alternatively use the path

http://vhmthphy.vhcc.edu/ > General Information > Startup and Orientation (either scroll to bottom of page or click on Links to Supplemental Sites) > typewriter notation examples

and you will find a page containing a number of additional exercises and/or examples of typewriter notation.Locate this site, click on a few of the links, and describe what you see there.

......!!!!!!!!...................................

RESPONSE -->

It gives examples of trypewriter notation as well as their standard forms.

confidence assessment: 3

.................................................

......!!!!!!!!...................................

13:57:14

You should see a brief set of instructions and over 30 numbered examples. If you click on the word Picture you will see the standard-notation format of the expression. The link entitled Examples and Pictures, located in the initial instructions, shows all the examples and pictures without requiring you to click on the links. There is also a file which includes explanations.

The instructions include a note indicating that Liberal Arts Mathematics students don't need a deep understanding of the notation, Mth 173-4 and University Physics students need a very good understanding,

......!!!!!!!!...................................

RESPONSE -->

I found this very helpful

self critique assessment: 2

.................................................

......!!!!!!!!...................................

13:57:36

while students in other courses should understand the notation and should understand the more basic simplifications.

There is also a link to a page with pictures only, to provide the opportunity to translated standard notation into typewriter notation.

......!!!!!!!!...................................

RESPONSE -->

self critique assessment: 0

.................................................

&#Good work. See my notes and let me know if you have questions. &#

&#It is recommended that you periodically review the document on responses and self-critiques located at http://vhcc2.vhcc.edu/dsmith/geninfo/labrynth_created_fall_05/levl1_22/levl2_81/file3_259.htm, which is relevant to your responses and self-critiques on this exercise. &#