The Chinese phrase Four Great Ancient Capitals of China (中国四大古都 pinyin zhong1 guo2 si4 da4 gu3 du1) refers to Nanjing, Beijing, Xi'an, and Luoyang.
... \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 ...