union and intrsection HELP!! 10 pts to best answer..?

Question

my algebra homework, im so confused. i have no idea how to get the answer. for example form probs 3-8, 3 is A (n sign) B. I HAVE NO IDEA HOW TO GET THE NUMBERS how the hell do you get numbers froma letter and the chart thing, my teacher made on the board with circles and i'm so lost.

Answer 1

First you have to remember the definitions:

Set - a set is a collection of objects, things, etc. that are related to each other and has a common attribute or properties. A set is usually denoted or identified by a name or a letter of the aphabet. For example, Set A, set B, set C, and so on. A set is normally represented by a circle.

Element - is an object, thing, etc. that belongs to a Set. An element is usually represented by putting it inside a Set.

Example 1:

Set A = { pets }
Set A = { dog, cat, rabbit, parrot, frog, gold-fish, pony }

We can say, Set A is a collection of pets. Dog is an element of Set A. Cat is another element of Set A. Dog, cat, rabbit, parrot, frog, goldfish, pony are all elements of Set A.


Example 2:
Set B = { wild animals }
Set B = { tiger, lion, eagle, crocodile, phyton, bear, vulture }

Operations:
Union - is the combination of two or more sets. It is denoted by "U".
Intersection - an attribute or property that is common between two or more sets. It is denoted by "n".

Example 3 (Union operation):
{ animals } = { pets } U { wild animals } = (Set A) U (Set B)

{ animals } = { dog, cat, rabbit, parrot, frog, gold-fish, pony } U { tiger, lion, eagle, crocodile, phyton, bear, vulture }

{ animals } = { dog, cat, rabbit, parrot, frog, gold-fish, pony, tiger, lion, eagle, crocodile, phyton, bear, vulture }


Example 4 (Intersection operation):
{ birds } = { pets } n { wild animals} = (Set A) n (Set B)

{ birds } = { dog, cat, rabbit, parrot, frog, gold-fish, pony } n { tiger, lion, eagle, crocodile, phyton, bear, vulture }

{ birds } = { parrot, eagle, vulture } --->parrot is the only bird in Set A, and eagle and vulture are the only birds in Set B.

I guess that you now have an idea of the basic principles of Sets and their Operations.

Going back to your question, the details that you have given is not complete. But I will give you an example from them.

Set A = { range of whole numbers from 3 to 8}
Set A = { 3, 4, 5, 6, 7, 8 }

Set B = { range of numbers from 1 to 3 }
Set B = { 1, 2, 3 }

Operations:

(Set A) U (Set B) = { 3, 4, 5, 6, 7, 8 } U { 1, 2, 3 }
(Set A) U (Set B) = {1, 2, 3, 4, 5, 6, 7, 8} ---> this is the combined set of numbers from Set A and Set B

(Set A) n (Set B) = { 3, 4, 5, 6, 7, 8 } n { 1, 2, 3 }
(Set A) n (Set B) = { 3 } ---> this is the number that is common to both Set A and Set B (the only number that can be found in both Set A and Set B.

See the links below for more detailed explanation of the concept.

Answer 2

Somewhere, you have a list of the objects contained in A and of the objects contained in B.

From your reaction, I guess they are numbers.

A intersection B will include any number that is in A AND in B. If a number is in A but not in B, it is not in the intersection. It is possible for an intersection to be empty (for example, if A has only even numbers and B has only odd numbers).

A union B includes any number that is in A or in B. It includes the numbers that are in both. A union can only be empty if both A and B are empty. As soon as one set contains something, then that something also belongs to the union.