Question

Find all subsets for the set: B = {4,5,7}

Answer 1

{4},{5},{7},{4,5},{4,7},{5,7},{4,5,7} ? is it this

Answer 2

You're missing \(\emptyset \) which is a subset of all sets.
For n elements in a set, there are \(2^n\) subsets.

Answer 3

{},{4},{5},{7},{4,5},{4,7},{5,7},{4,5,7}

Answer 4

?

Answer 5

these are my only choices ?

Answer 6

{},{4},{5},{7},{4,7},{5,7},{4,5,7}

{},{4},{5},{7},{4,5},{4,7},{4,5,7}

{},{4},{5},{7},{4,5},{4,7},{5,7},{4,5,7}

{4},{5},{7},{4,5},{4,7},{5,7},{4,5,7}

Answer 7

and this one to makes no sense?

Answer 8

The number square root of 9 belongs to which set of numbers?

I,R,C

N,W,Z,Q,R,C

Z,Q,R,C

Q,R,C

Answer 9

@mathmate

Answer 10

Yes, you need the choice that contains the 7 you mentioned plus {}, making a total of \(2^3\)subsets.

Answer 11

for the first question?

Answer 12

Yes, the subsets of {4,5,7}.
I'll get to the second one in a minute. takes a lot of typing.
Have you done the sets of numbers? Z for integers, etc.?

Answer 13

so the answer would be {},{4},{5},{7},{4,5},{4,7},{5,7},{4,5,7}

Answer 14

nope I really dont understand this question

Answer 15

There are 5 predefined sets of numbers:
N=natural numbers
Z=integers
Q=rational numbers
C=complex numbers and
R=real numbers.
You may want to read up some articles for the precise definition of each, for example at:
http://en.wikipedia.org/wiki/Number_system#Classification_of_numbers
then the question will make a lot more sense.

Answer 16

ok

Answer 17

but the number

Answer 18

or I mean letters of sq root 9

Answer 19

I dont understand what it would be

Answer 20

Can you give me the square root of 9?

Answer 21

3

Answer 22

Good, but you know -3 is also the square root of 9, right?

Answer 23

no

Answer 24

why

Answer 25

The square-root of N is a number which when multiplied by itself will give N.
(3)*(3)=9
and
(-3)(-3)=9
So since both 3 and -3 satisfy this definition, so both of them are square-roots of 9.
Does that make sense?

Answer 26

why n

Answer 27

N=9 in this case.

Answer 28

i dont get the letters

Answer 29

ohh ok

Answer 30

I'll rephrase the definition of square-root.
The square-root of the number X is a number which when multiplied by itself will give X.
In this case, we're talking about X=9.
Is that better?

Answer 31

N,W,Z,Q,R,C

Answer 32

This is a completely different thing.
Remember I mentioned that there are 5 pre-defined sets, which you probably have learned at school?
If you need a review, go to
http://en.wikipedia.org/wiki/Number_system#Classification_of_numbers

The question is asking you to which of the 5 sets do 3 and -3 belong.
The choice that has W does not make any sense, because W is not a pre-defined set of numbers. Only the 5 I mentioned are (N,Z,Q,R,C). If the choice contain any letter outside of these 5, it is automatically not a valid choice.

Answer 33

umm sorry im lost here

Answer 34

whats the answer

Answer 35

You will need to check if -3 and +3 satisfy which of the 5 classes of numbers. Those sets (letters) that contain -3 and 3 will qualify. Put them together and make the choice.

For example, 3 is an integer, so it belongs to the set Z.
Again, use the link to help you recall what you learned in class.
http://en.wikipedia.org/wiki/Number_system#Classification_of_numbers

Answer 36

z,q,r,c?

Answer 37

exactly! Good job!

Answer 38

good thanks

Answer 39

one more?

Answer 40

. Find the elements in the set: B = {2x | x is a Whole Number}


{...-6,-4,-2,2,4,6,...}

{0,2,4,6,8,...}

{...-6,-4,-2,0,2,4,6,...}

{2,4,8,16,32,..}

Answer 41

would this be the lcd ?

Answer 42

or factors of 2

Answer 43

@mathmate

Answer 44

They should all be even numbers.

Answer 45

ok so is it{2,4,8,16,32,..}

Answer 46

It depends on the interpretation of "whole number".

Answer 47

There are three usages of whole numbers"
{...-3,-2,-1,0,1,2,3,4,...}
{0,1,2,3...}
or
{1,2,3,4...}
Which one does your teacher use?

Answer 48

its online

Answer 49

no teacher

Answer 50

Can you look back to see the definition of whole number?
A and D are definitely out, because A is missing a zero in between, and D is missing 6,10,12...

Answer 51

yea a whole number contains no fractions i know

Answer 52

That's correct but not sufficient.
You need to know your course material defines a whole number to include or exclude 0, or negative numbers.

Answer 53

numbers 0,1,2,3,4, and so on

Answer 54

ok

Answer 55

Good, then you can make you choice! :)

Answer 56

ok it accepts 0

Answer 57

i know

Answer 58

but are negatives okk

Answer 59

i think its just 0,2,4,6,8

Answer 60

There are 3 common usages of the term "whole number" (which incidentally is not mathematical, that's why the ambiguities):
{...-3,-2,-1,0,1,2,3,4,...}
{0,1,2,3...}
or
{1,2,3,4...}
It depends on your course which is responsible for clarifying which one it uses.

Answer 61

Sorry, got to go!

Answer 62

ok

Answer 63

If you cannot find the definition of "whole numbers" as per your online notes, go for 0,2,4,... as you suggested and see what happens.