Sets

Question 1

∩

Answer 1

Intersection: elements that both sets have in common.
e.g. A ∩ B = {c, f}

Question 2

∪

Answer 2

Union: the elements in both sets listed once.
e.g. A ∪ B = {a, c, d, e, f, g}

Question 3

∈

Answer 3

is an element of
e.g. g ∈ A and k ∈ B

Question 4

∈ with a line through it

Answer 4

is not an element of

Question 5

∅ or { }

Answer 5

Null set
e.g. if D = set of weekdays beginning with ‘G’ then D = { } or D = ∅

Question 6

c

Answer 6

Is a subset of
If all elements of a set are in another set then 1 set = a subset of the other.
e.g. {c, g} c A because c + g are in set A

Question 7

’

Answer 7

Complement: elements that are NOT in a set.
e.g. A’ = { b, d, h, i, j, k } and B’ = { a, b, e, g, i, j }

Question 8

A\B

Answer 8

A without B
The set of A with no values that are in B

Question 9

#

Answer 9

Cardinal Number: number of elements in a set
e.g. #A = 5 and #U = 11