Orientation

course mth 151

I have to get the cds to do the next part.

ˆ|}\׹xassignment #001

Your work has been received. Please scroll through the document to see any inserted notes (inserted at the appropriate place in the document, in boldface) and a note at the end. The note at the end of the file will confirm that the file has been reviewed; be sure to read that note. If there is no note at the end, notify the instructor through the Submit Work form, and include the date of the posting to your access page.

001. Only assignment: prelim asst

qa prelim

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10:15:35

`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?

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RESPONSE -->

Yes.

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10:17:48

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.

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RESPONSE -->

Yes I've found it

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10:19:34

`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.

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RESPONSE -->

The information that is typed in the answer box is saved to the Send file and even if there is a problem with this application, the answers will still be in that file.

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10:22:17

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.

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RESPONSE -->

Ok, I already have an access code.

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10:22:45

`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.

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RESPONSE -->

i understand

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10:24:32

Once more, locate the SEND file in your c:\vhmthphy folder, and open the file. Copy its contents to the clipboard (this is a common operation, but in case you don't know how, just use CTRL-A to highlight the contents of the file and CTRL-C to copy the contents to the clipboard). Then return to the form that instructed you to run this program, and paste the contents into the indicated box (just right-click in the box and select Paste).

You may now click on the Quit button, or simply close the program.

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RESPONSE -->

ok

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wHZִ̫谮

assignment #001

001. typewriter notation

qa initial problems

01-14-2007

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11:45:56

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

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RESPONSE -->

The first expression indicates, according to the order of operations rule, that 2 must be divided by x first. The second expression contains the parenthesis, so you must solve what is in the parenthesis first then divide the two answers.

With the second expression, when 2 is plugged in for x there is a zero in the denominator, which automatically makes the answer zero. with the first expression, when 2 is plugged in to the expression becomes 2-2/2+4. So you must divide first which makes it 2-1+4 then solve left to right, which is 5.

confidence assessment: 3

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11:47:17

The order of operations dictates that grouped expressions must be evaluated first, that exponentiation must be done before multiplication or division, which must be done before addition or subtraction.

It makes a big difference whether you subtract the 2 from the x or divide the -2 by 4 first. If there are no parentheses you have to divide before you subtract. Substituting 2 for x we get

2 - 2 / 2 + 4

= 2 - 1 + 4 (do multiplications and divisions before additions and subtractions)

= 5 (add and subtract in indicated order)

If there are parentheses you evaluate the grouped expressions first:

(x - 2) / (x - 4) = (2 - 2) / ( 4 - 2) = 0 / 2 = 0.

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RESPONSE -->

i understand

self critique assessment:

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11:47:25

The order of operations dictates that grouped expressions must be evaluated first, that exponentiation must be done before multiplication or division, which must be done before addition or subtraction.

It makes a big difference whether you subtract the 2 from the x or divide the -2 by 4 first. If there are no parentheses you have to divide before you subtract. Substituting 2 for x we get

2 - 2 / 2 + 4

= 2 - 1 + 4 (do multiplications and divisions before additions and subtractions)

= 5 (add and subtract in indicated order)

If there are parentheses you evaluate the grouped expressions first:

(x - 2) / (x - 4) = (2 - 2) / ( 4 - 2) = 0 / 2 = 0.

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RESPONSE -->

self critique assessment:

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11:51:01

`q002. Explain the difference between 2 ^ x + 4 and 2 ^ (x + 4). Then evaluate each expression for x = 2.

Note that a ^ b means to raise a to the b power. This process is called exponentiation, and the ^ symbol is used on most calculators, and in most computer algebra systems, to represent exponentiation.

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RESPONSE -->

the first problem expresses that you should raise 2 to the xth power then add 4 to the resulting answer. the second problem indicates that you raise 2 by the x plus four power. The first problem is 2^2+4 which is 4+4 which equals 8. the second problem is 2^6 which is 64.

confidence assessment: 3

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11:51:40

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 ].

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RESPONSE -->

ok

self critique assessment: 3

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11:55:53

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

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RESPONSE -->

first you would substitute four in for x which would give you (4-5)^8-1+3/4-2. next you would solve for the parenthesis. -1^8-1+3/4-2 next you must raise -1 to the 8 th power. 1-1+3/4-2. Next you must divide 3 by 4. Next you simply work left to right, which is -1 and 1/4.

confidence assessment: 2

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11:57:39

*&*& 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.

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RESPONSE -->

ok

self critique assessment:

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.

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The third question is missing. Be sure you understand. Also note the need for self-critique on #4.