Section R1

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course Mth 158

If your solution to stated problem does not match the given solution, you should self-critique per instructions at http://vhcc2.vhcc.edu/dsmith/geninfo/labrynth_created_fall_05/levl1_22/levl2_81/file3_259.htm.

Your solution, attempt at solution:

If you are unable to attempt a solution, give a phrase-by-phrase interpretation of the problem along with a statement of what you do or do not understand about it.This response should be given, based on the work you did in completing the assignment, before you look at the given solution.

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Question: * R.1.26 \ was R.1.14 (was R.1.6) Of the numbers in the set {-sqrt(2), pi + sqrt(2), 1 / 2 + 10.3} which are counting numbers, which are rational numbers, which are irrational numbers and which are real numbers?

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Your solution:

Counting numbers: none

Rational numbers: ½, 10.3

Irrational numbers: {-sqrt(2), sqrt(2)}

Real numbers: all

confidence rating #$&*:ok

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Given Solution:

* * ** Counting numbers are the numbers 1, 2, 3, .... . None of the given numbers are counting numbers

Rational numbers are numbers which can be expressed as the ratio of two integers. 1/2+10.3 are rational numbers.

Irrational numbers are numbers which can be expressed as the ratio of two integers. {-sqrt(2)}, pi+sqrt(2) are irrational numbers.. **

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Self-critique (if necessary):ok

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Self-critique Rating:ok

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Question: * R.1.44 \ 32 (was R.1.24) Write in symbols: The product of 2 and x is the product of 4 and 6

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Your solution:

The answer is 2*x=4*6

confidence rating #$&*:ok

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Given Solution:

* * ** The product of 2 and x is 2 * x and the product of 4 and 6 is 4 * 6. To say that these are identical is to say that 2*x=4*6. **

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Self-critique (if necessary):ok

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Self-critique Rating:ok

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Question:

* R.1.62 \ 50 (was R.1.42) Explain how you evaluate the expression 2 - 5 * 4 - [ 6 * ( 3 - 4) ]

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Your solution:

To complete this problem I simply followed the order of operations. The first operation we perform is the 3-4 inside parenthesis and inside brackets this gives the problem 2-5*4-[6*(-1)]. Now we perform the indicated operation inside the brackets which gives 2-5*4-[-6]. Now we distribute the negative and the problem becomes 2-5*4+6 and now we perform the multiplication which gives 2-20+6. Now we do the operations in order so 2-20=-18+6=-12. So the answer to this problem is -12.

confidence rating #$&*:ok

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Given Solution:

* * **Starting with

2-5*4-[6*(3-4)]. First you evaluate the innermost group to get

2-5*4-[6*-1] . Then multiply inside brackets to get

2-5*4+6. Then do the multiplication to get

2-20+6. Then add and subtract in order, obtaining

-12. **

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Question: * R.1.98 \ 80 (was R.1.72) Explain how you use the distributive property to remove the parentheses from the express (x-2)(x-4).

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Your solution:

To remove the parenthesis I used the foil method. So I multiplied first then outer then inner and the last giving me the trinomial of x^2-6x+8.

confidence rating #$&*:ok

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Given Solution:

* * ** COMMON ERROR: Using FOIL. FOIL is not the Distributive Law. FOIL works for binomial expressions. FOIL follows from the distributive law but is of extremely limited usefulness and the instructor does not recommend relying on FOIL.

Starting with

(x-2)(x-4) ; one application of the Distributive Property gives you

x(x-4) - 2(x-4) . Applying the property to both of the other terms we get

x^2 - 4x - (2x -8). Simplifying:

x^2 - 4x - 2x + 8 or

x^2 - 6x + 8. *

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Self-critique (if necessary):

When solving this problem I in fact used the foil method and the answer I received from using this technique was correct, however I understand your point. That it might have worked this time but it won’t work for all times therefore making it unreliable. So what you did was split the first term into two and multiplied each half by the second term. I understand this now.

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Self-critique Rating:2

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Good.

FOIL will always work for binomials, but it only works for binomials. Students who learn FOIL often fail to learn the much more basic and important distributive law, which is why I object to FOIL.

However as long as you know the distributive law, it won't hurt you to sneak and use FOIL once in awhile. Just try not to let me know.

*@

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Question:

* R.1.102 \ 86 (was R.1.78) Explain why (4+3) / (2+5) is not equal to 4/2 + 3/5.

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Your solution:

They are not equal because the orders of operations are different in each problem. For example in (4+3)/ (2+5) you would perform the addition in the parenthesis then division. Therefore the answer would be 7 but for the second problem the division is done first and we are dividing different terms. In the first we are dividing the sum of 4 and 3 by the sum of 2 and 5, in the second we are dividing 4 by 2 and 3 by 5 then adding the quotients.

confidence rating #$&*:ok

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Given Solution:

* * ** Good answer but at an even more fundamental level it comes down to order of operations:

(4+3)/(2+5) means

7/7 which is equal to

1.

By order of operations, in which multiplications and divisions precede additions and subtractions,

4/2+3/5 means

(4/2) + (3/5), which gives us

2+3/5 = 2 3/5

* Add comments on any surprises or insights you experienced as a result of this assignment.

One surprise I had while completing this assignment was the advisory not to use the foil method. I can understand why we shouldn’t use it now, but for many classes previously taken the foil method was preached as gospel.

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Self-critique (if necessary):

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Self-critique rating:

&#Your work looks good. See my notes. Let me know if you have any questions. &#