002 Query 2

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course Mth 151

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.

002. `Query 2

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Question: `q2.2.24 U={a,b,...,g}, A={a,e}, B={a,b,e,f,g}, C={b,f,g}, D={d,e} Is C ps U?

Is the statement true or false and why?

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Your solution:

True All the elements in C are in U and C is not identical to U

confidence rating #$&*: 3

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Given Solution:

`a** It's true because all elements of C are in the universal set, and because there are elements of U that aren't in C. You have to have both conditions, since a proper subset cannot be identical to other set. **

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Self-critique (if necessary):OK

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Self-critique Rating:3

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Question: `qQuery 2.2.30 phi s D

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Your solution:

Yes The empty set is a subset of any set.

confidence rating #$&*:3

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Given Solution:

`a** Note that You should be responding to problem 2.2.30 from the homework you worked out on paper. The shorthand notation is for my reference and won't always make sense to you. For clarification, though, the symbol for the empty set is the Greek letter phi.

One set is a subset of another if every element of that set is in the other. To show that a set isn't a subset of another you have to show something in that set that isn't in the other.

There's nothing in the empty set so you can never do this--you can never show that it has something the other set doesn't. So you can never say that the empty set isn't a subset of another set.

Thus the empty set is a subset of any given set, and in particular it's a subset of D.

ALTERNATIVE ANSWER: As the text tells you, the empty set is a subset of every set.

ANOTHER ALTERNATIVE

Every element of the empty set is in D because there is no element in the empty set available to lie outside of D.

ONE MORE ALTERNATIVE: The empty set is a subset of every set. Any element in an empty set is in any set, since there's nothing in the empty set to contradict that statement. **

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Self-critique (if necessary):OK

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Self-critique Rating:3

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Question: `q2.2.33 D not s B

Is the statement true or false and why?

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Your solution:

True d is in D but is not in B.

confidence rating #$&*: 3

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Given Solution:

`a** D is a subset of B if every element of D is an element of B-i.e., if D doesn't contain anything that B doesn't also contain.

The statement says that D is not a subset of B. This will be so if D contains at least one element that B doesn't. **

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Self-critique (if necessary):OK

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Self-critique Rating:3

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Question: `q2.2.36 there are exactly 31 subsets of B

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Your solution:

False B has 5 elements so the number of subsets is 2^5=32

confidence rating #$&*: 3

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Given Solution:

`a** If a set has n elements then is has 2^n subsets, all but one of which are proper subsets. B has 5 elements so it has 2^5 = 32 subsets. So the statement is false.

There are exactly 31 proper subsets of B, but there are 32 subsets of B. **

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Self-critique (if necessary):OK

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Self-critique Rating:3

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Question: `qQuery 2.2.40 there are exactly 127 proper subsets of U

Is the statement true or false and why?

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Your solution:

True U has 7 elements so the number of subsets is 2^7=128. The set, U, is not a proper subset of itself so there are 227 ps

confidence rating #$&*: 3

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Given Solution:

`a** The set is not a proper subset of itself, and the set itself is contained in the 2^n = 2^7 = 128 subsets of this 7-element set. This leaves 128-1 = 127 proper subsets. **

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Self-critique (if necessary):OK

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Self-critique Rating:3

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Question: `qQuery 2.2.48 U={1,2,...,10}, complement of {2,5,7,9,10}

What is the complement of the given set?

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Your solution:

{1,3,4,6,8} All elements of U not in the given set.

confidence rating #$&*: 3

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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Given Solution:

`a** the complement is {1,3,4,6,8}, the set of all elements in U that aren't in the given set. **

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Self-critique (if necessary):OK

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Self-critique Rating:3

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Question: `qQuery 2.2.48 U={1,2,...,10}, complement of {2,5,7,9,10}

What is the complement of the given set?

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Your solution:

{1,3,4,6,8} All elements of U not in the given set.

confidence rating #$&*: 3

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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Given Solution:

`a** the complement is {1,3,4,6,8}, the set of all elements in U that aren't in the given set. **

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Self-critique (if necessary):OK

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Self-critique Rating:3

#*&!

&#Very good responses. Let me know if you have questions. &#