quadratic equation

• The discussion of the fourth kind of quadratic equation , the use of " rule of three " , the calculation of number r and some terms algebra can be found in indian classics introduced to arab and some of these mathematical knowledge maybe comes from china ( such as " rule of three " )
  花拉子米对第四种二次方程的讨论，使用的“三率法” ，对圆周率的计算以及某些术语可以在早期传入阿拉伯的印度典籍中找到出处，而在这些数学知识中有一些可能是远源于中国的（比如“三率法” ） 。