note: Australia's last aircraft carrier fleet was decommissioned in 1982. The current Sydney and Melbourne are guided missile frigates, and the current Albatross is a naval base on land near Nowra[?].
... \sqrt {b^2-4ac}</math>
in the formula should be understood as "either of those element(s) of the field whose square equals b2 - 4ac". In some fields, so ...