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.
... of the coefficients a, b and c, which are assumed to be real (but see below for generalizations) with a being non-zero. These solutions are also called the roots of th ...