Thread: Please help! After the union, A u B, A = [-3, 8), B = (6,8]

Originally Posted by adamb

A = [-3, 8)
B = (6,8] So A u B is?
Really confused about it, can you please help?

How can you possibly be confused? Do you know the definitions?
$A\cap B= (6,8)$ WHY?
So $A\cup B=~?$

A u B = (-3,6,8)

Originally Posted by adamb

A u B = (-3,6,8)

Can you tell us why you do not even understand the notation before posting a question?
I want to think that you are not an internet troll. This kind of ignorance point to an otherwise conclusion.

Do you know how the set $(3,6)$ is even defined?
Do you know what union means?
Do you have any idea what any of this is about?

If not, then you are a troll. Please prove us wrong.

Im not trolling anyone here. I understand that A = [-3, 8) and B = (6, 8]
Im wondering since the notation () and [] are being used does this mean the set
A contains -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7
and
B contains 7, 8
so A u B is = 7?
is this correct?
or does A just contain [-3, 8) -3 and 8 and B (6, 8] just 6 and 8?
so A u B is = (-3, 6, 8)?

Originally Posted by adamb

Im not trolling anyone here. I understand that A = [-3, 8) and B = (6, 8]
Im wondering since the notation () and [] are being used does this mean the set
A contains -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7
and
B contains 7, 8
so A u B is = 7?
is this correct?
or does A just contain [-3, 8) -3 and 8 and B (6, 8] just 6 and 8?
so A u B is = (-3, 6, 8)?

Something you have to understand is that [-3,8), for example, stands for all the real numbers between -3 and 8, including -3, not including 8. It's not just the integers.

So you want the union of A = the set of all real numbers between -3 and 8, including -3 but not 8, and B = the set of all real numbers between 6 and 8, including 8 but not 6.

The union is (by definition) the set of all real numbers in either A or B.

Now is it easier to see the solution?

- Hollywood