Understand the formal definition and notation of functions
A function is a rule that assigns exactly one output to each input.
A function from set to set is a rule that assigns to each element in exactly one element in .
To find when :
A graph represents a function if and only if no vertical line intersects the graph more than once.
✓ is a function (parabola passes test) ✗ is not a function (circle fails test)
Functions can have restricted domains:
Domain: All real numbers except
Domain:
Domain: