# Thread: List the (distinct) elements in each of the following set:

1. ## List the (distinct) elements in each of the following set:

I am not sure what these problems are requesting. I have watched Discrete Math videos and read my textbook, still unable to arrive at the answers.

List the (distinct) elements in each of the following set:
1e.) {aÎN | a < -4 and a > 4}

Let A = {(-1,2), (4,5), (0,0), (6,-5), (5,1), (4,3)}
List the elements in each of the following sets.
3b.) {a | a > 0 and (a,b) Î A for some b}

4.) List the elements in the sets A={a,b) Î N x N | a≤b, b≤3} and B={a/b Î {-1,1,2} }.

2. ## Re: List the (distinct) elements in each of the following set:

Originally Posted by rtrumpow
I am not sure what these problems are requesting. I have watched Discrete Math videos and read my textbook, still unable to arrive at the answers.

List the (distinct) elements in each of the following set:
1e.) {aÎN | a < -4 and a > 4}
You can't, strictly speaking, list the elements because there are an infinite number of them. Is it possible that the problem actually said "a> -4" and "a< 4"? In addition, "N" usually means the positive integers. If that is the case here, the reference to "-4" is irrelevant.

Let A = {(-1,2), (4,5), (0,0), (6,-5), (5,1), (4,3)}
List the elements in each of the following sets.
3b.) {a | a > 0 and (a,b) Î A for some b}
The only requirement is that "a> 0" and only (-1, 2) and (0, 0) don't satisfy that.

4.) List the elements in the sets A={a,b) Î N x N | a≤b, b≤3} and B={a/b Î {-1,1,2} }.
If " $a\le b$", a/b can't be 2. And "a/b= -1" isn't possible for for a and b both positive numbers. That leaves only "a/b= 1" and b can only be 1, 2, or 3.

3. ## Re: List the (distinct) elements in each of the following set:

Question 1e.) is accurate. I verified with the textbook that I did not switched the signs.

4. ## Re: List the (distinct) elements in each of the following set:

I'm really confused with question 4. My textbook shows B= {a/b | a,b belongs to {-1,1,2}} I thought that the sets A= and B= would be two different answers but they're all one? This discrete math is killing me please help

5. ## Re: List the (distinct) elements in each of the following set:

Originally Posted by laurm
My textbook shows B= {a/b | a,b belongs to {-1,1,2}}
This means all possible expressions of the form $a/b$ where $a$ and $b$ range over $-1$, $1$ and $2$.