What do parentheses with bumps mean?

Answer 1

You mean these?: { } If you do, in math they indicate roster notation.

Roster Notation- used to write sets of numbers.

Example:
{0,1,2,3,4...} The dots indicate that the numbers go all the way to infinity.

Braces can also be used in Finite sets. Here are some:

A={2,4,6,8,10}
B={1,2,3,4,5} Where do these intersect?

Intersection symbol: Upsidedown "U"

Set A intersects B. The answer is {2,4} Intersection is all the numbers that 2 finite sets share.

Union symbol: U

Set A U B. The answer is {1,2,3,4,5,6,8,10} If you noticed, the set includes all of the numbers from sets A and B, not repeating any numbers. It's always best to put them in order from least to greatest so it doesn't get confusing.

OH, and if there are no intersections, you use the null set:a zero with a diagonal slash through it OR you can use the empty set: { } Both mean the same. You use Double bar R for sets that are exactly the same.

Hope this helps!! :D