Burma's Pagan empire begins to disintegrate after being defeated by Kublai Khan at Ngasaungsyan[?], near the Chinese border. The Khan ordered the invasion after the Burmese refused to pay tribute.
... formula expresses the explicit solution(s) x to the quadratic equation
<math>ax^2+bx+c=0</math>
in terms of the coefficients a, b and c, which are assumed to ...