Operations on Sets
Intersection
The set of elements common to two sets, written A ∩ B.
| English | Intersection |
|---|---|
| Bahasa Melayu | Persilangan |
| 中文 | 交集 |
How it is used
Let P = {multiples of 2 up to 12} = {2, 4, 6, 8, 10, 12} and Q = {multiples of 3 up to 12} = {3, 6, 9, 12}. Then P ∩ Q = {6, 12}, the numbers that are multiples of both 2 and 3.
Where it shows up in SPM
In the Operations on Sets chapter (Form 4). Paper 1 asks you to list the intersection of number sets defined by a rule; Paper 2 combines it with union and complement in a single Venn-diagram problem.
Don't confuse it with
Open the chapter: Operations on Sets →
Frequently asked questions
How do I find the intersection of sets given by a rule, not a list?
First list the elements of each set from the rule, then pick the ones in both. For {factors of 12} ∩ {factors of 18}: factors of 12 are 1, 2, 3, 4, 6, 12 and of 18 are 1, 2, 3, 6, 9, 18, so the intersection is {1, 2, 3, 6}.
Can the intersection of three sets be found the same way?
Yes. For A ∩ B ∩ C, keep only elements that appear in all three.
If A = {1, 2, 3, 4}, B = {2, 3, 4, 5} and C = {3, 4, 5, 6}, the common elements are {3, 4}.