Note: Australia is generally considered to be a continental landmass, rather than an island. If however one does count Australia among the islands it, not Greenland, would be the largest in the world (unless one also considered Antarctica an island).
... 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 should ...