Solving Sets: (A intersects B) - C

[Bucs44]

Homework Statement

Here is the problem that I want to make sure I have an understanding of:

(A intersects B) - C

Given the following sets: A= {1,4,7,10} B= {1,2,3,4,5} C= {2,4,6,8}

Order of operations tells me to do what's in parentheses first. A intersecting B which gives me {1, 4}

Now minus C is where I'm a little fuzzy - I think the final answer is {4} because I took out the number that wasn't in set C - being 1.

Am I on the right track?

 

[matt grime]

What is the definition of X\Y or X-Y in your notes?

 

[Bucs44]

The difference X - Y consists of all elements in X that are not in Y

 

[matt grime]

So apply the definition to the sets.

 

[Bucs44]

Right - so the answer is 4

 

[HallsofIvy]

?
YOU just said "The difference X - Y consists of all elements in X that are not in Y" (added emphasis). So (A intersect B)- C consists of all elements of (A intersect B) that are not in C. And C= {2, 4, 6, 8}.
Which of 1 and 4 is not in C?

 

[Bucs44]

Okay - I had it backwards - 1 is not in C