Solution Sets Help plz

[Jenny!]

I don't get when your solution set is all R, {}, (-x,x), (-infinity,-x)U(x,infinity). This is for inequalities btw.

For example.

x<11 x>-11

Choose the solution set

A.(-11,11)

B.(-infinity,-11)U(11,infinity).

C. [-11,11]

D. (-infinity,-x]U[x,infinity).

E. R

F. {}

I don't get problems like these. Obvious C+D are eliminated because there are no blahblah-or equal to. So that leaves A, B, E, F. I know R means ALL REAL NUMBERS, but it there can't be 11 or -11, right? So R could only be used if it was greater/lesser than or equal to, right? I have no idea what {} is or anything at all. A is just a coordinate to me, I don't understand how it could be a viable option then B, I don't know.

Help.

Nevermind. I think I got it. R means all Real numbers inbetween and {} means no solutions.Yeah!?

But when are

A.(-11,11)

B.(-infinity,-11)U(11,infinity).

Used?

[x42bn6]

Originally Posted by Jenny!

I don't get when your solution set is all R, {}, (-x,x), (-infinity,-x)U(x,infinity). This is for inequalities btw.

For example.

x<11 x>-11

Choose the solution set

A.(-11,11)

B.(-infinity,-11)U(11,infinity).

C. [-11,11]

D. (-infinity,-x]U[x,infinity).

E. R

F. {}

I don't get problems like these. Obvious C+D are eliminated because there are no blahblah-or equal to. So that leaves A, B, E, F. I know R means ALL REAL NUMBERS, but it there can't be 11 or -11, right? So R could only be used if it was greater/lesser than or equal to, right? I have no idea what {} is or anything at all. A is just a coordinate to me, I don't understand how it could be a viable option then B, I don't know.

Help.

Nevermind. I think I got it. R means all Real numbers inbetween and {} means no solutions.Yeah!?

But when are

A.(-11,11)

B.(-infinity,-11)U(11,infinity).

Used?

Yes. I think you should be familiar with set notation: {} is quite bad notation because one can interpret this as a set with a space in it, so you get the o with a line through it (empty set; nullity). R is the set of all real numbers (in one dimension).

There are no doubt equations with solution set (-11,11). For example, -11<x<11. As for (-infinity,-11)U(11,infinity), you can easily use x<-11, x>11 (making the answer B).

Why is it not D? D includes the values -11 and 11, which is not in your question. D would be the solution set of x<=-11, x>=11.*

[Eric]

X42, can you teach me math someday?

[x42bn6]

Sure, but Wikipedia and MathWorld are the best places.*

[Jenny!]

Originally Posted by x42bn6

Yes. I think you should be familiar with set notation: {} is quite bad notation because one can interpret this as a set with a space in it, so you get the o with a line through it (empty set; nullity). R is the set of all real numbers (in one dimension).

There are no doubt equations with solution set (-11,11). For example, -11<x<11. As for (-infinity,-11)U(11,infinity), you can easily use x<-11, x>11 (making the answer B).

Why is it not D? D includes the values -11 and 11, which is not in your question. D would be the solution set of x<=-11, x>=11.*

The answer was E. I understand {} and R, but I guess (-11,11) could only be the answer if the equality/inequality is one long strain like you made? How can you have the equation x<=-11, x>=11? The next problem was set up like this granted w/o the same numbers and the answer was F. I also got it because I assumed {} meant it was an incorrect equality/inequality because I don't see how you can have a number thats equal/less than -11 but STILL greater than 11.

Like I said. D is eliminated because it includes them. I know <'s >'s never use []'s but <=, >= do.

[lollercoasterzster]

actually, it's A, I think you read your greater than/less than signs backwards x42. hmm wait are the x<11 and x>-11 supposed to be two separate conditions? I don't really see what's going on... msut be too late for me...

[Jenny!]

Yeah. They're separate. I think if they were together you would be right.

[x42bn6]

Originally Posted by Jenny!

The answer was E. I understand {} and R, but I guess (-11,11) could only be the answer if the equality/inequality is one long strain like you made? How can you have the equation x<=-11, x>=11? The next problem was set up like this granted w/o the same numbers and the answer was F. I also got it because I assumed {} meant it was an incorrect equality/inequality because I don't see how you can have a number thats equal/less than -11 but STILL greater than 11.

Like I said. D is eliminated because it includes them. I know <'s >'s never use []'s but <=, >= do.

It cannot be E: The solution set from your question does not include the value 1, for example, but R does...

I think you know that [ and ] mean to include the upper/lower bound in the set. However, (-11,11) cannot be the answer irregardless of the notation because this is the set of all real numbers from -11 to 11 exclusive, which is almost the compliment of the question's requirement.

As for x<=-11, x>=11, you asked for a scenario and I gave you one.*

[TrongaMonga]

]-∞,-1] V ]1,+∞[, that's how I represent intervals...

This one goes from -∞, open, since it's undefined, to -1 closed, and then from 1 open (1 is not part of the interval), to +∞, also open since it's undefined.

Meaning, that interval is |R except the interval starting in the first infinitesimal point at right of -1 to 1, included.

How do you folks define that?

[x42bn6]

I assume we can close ∞ and write [-∞,x] - it makes no real difference since ∞ is undefined - so (∞ and [∞ are really just a formality.

What I am bothered with is the fact that the solution is the following:

<-----------O                     O----------->
-∞ ... -12 -11 -10 ... 0 ... +10 +11 +12 ... +∞

Where the O is a non-filled circle, meaning the lower- and upper-bounds are not included. This cannot be R!*

[lollercoasterzster]

it's not B, you're reading the signs backwards. The first one says less than 11, the second one says greater than negative eleven, thus it is between -11 and 11. (-11,11). Looking at it this morning it turns out the answer is actually A. It can't be E because that implies it is all real numbers, and regardless of the interval in question we know it can't be -11 or 11. Since both conditions are separate, we know x is both greater than -11 and less than 11, and assuming this is the same x we're talking about... which it must be in this question, we can re-write this as -11<x<11, making the answer A.

[x42bn6]

I feel unbelievably stupid now.

However, that doesn't explain why the answer is E... But yeah, the answer is A then.*

[Jenny!]

Yeah. It is A. I think I ended up PICKING E and getting it wrong and misread the correction. WHOOPS!

Or this modular math program could be screwy, it happenz.

[Malcom Sex]

The values aren't included... the answer is C

[Jenny!]

Originally Posted by White and Nerdy

The values aren't included... the answer is C

Wrong. The only time you use [ ]'s is if it is <= and/or >=.

[x42bn6]

[ looks a lot more closed than (.*

[Lizardbreath]

Why don't you do your own hw jenny?

[x42bn6]

Because, like me, she is confused and confunded. *

[QuikSilver]

LOL....here is the answer guys...veryyyy simple...liks loler coasterzzz said
I am sure it is A!

Separate the question into 2 parts
X<11
and
x>-11

thus x must be between -11 and 11 right? AND x can not be 11 or -11 because of the greater and lesser signs(they are ≥ or ≤...which mean greater/less or equal!)...

The only answer that fits this is A...(-11,11)
The parenthesis denotes that the 11 and -11 are not included...a bracket would mean that the number adjacent to it is included...x42 read the signs backwards it seems...

[x42bn6]

No need to rub it in or I will give you Infractions humiliating me!1*