In classical geometry, a point is an entity that has no extent.
In the modern set theoretic approach to topology, this is formalised as: a point in a spaceX is simply an element of the set X.
... (In a field of characteristic 2, the element 2a is zero and it is impossible to divide by it.)
The symbol
<math>\pm \sqrt {b^2-4ac}</math>
in the formula ...