[tex]F=\{\ x\ |\ x<4\}\to F=(-\infty;\ 4)\\\\H=\{\ x\ |\ x\geq7\}\to H=[7;\ \infty)\\\\F\ \cap\ H=(-\infty;\ 4)\ \cap\ [7;\ \infty)=\O\\\\F\ \cup\ H=(-\infty;\ 4)\ \cup\ [7;\ \infty)[/tex]
F ∪ H is defined as the set that consists of all elements belonging to either set F or set H (or both).
F ∩ H is defined as the set composed of all elements that belong to both F and H
