Stage 19 · Sets & Intervals — the Language of Functions

19.2.5 Element-and-Set Membership

19.2 Writing a Set Down: Two Notations

Point 5 of 5

19.2.5 Element-and-Set Membership

Core idea

To say whether something is in the circle: write a∈A if it's in, a∉A if it's not.

Module goal. Master listing and rule-based notation, switching freely between "naming members one by one" and "stating one rule"
eastmath.com · 19.2 Writing a Set Down: Two Notations · 19.2.5 Element-and-Set Membership