Decades: 2020s 2030s 2040s 2050s 2060s - 2070s - 2080s 2090s 2100s 2110s 2120s
Years: 2070[?] 2071[?] 2072[?] 2073[?] 2074[?] 2075[?] 2076 2077[?] 2078[?] 2079[?]
... the formula should be understood as "either of those element(s) of the field whose square equals b2 - 4ac". In some fields, some elements have no square ...