Although the general method of his demonstrations about the cases of high degree equations is usually shown by concrete examples, his demonstrations on special cases are universal. 他对涉及高次方程的几何证明一般是通过具体例子来展示一般方法，但是，他针对特殊情形的证明方法具有一般性。
Descartes's solution of a depressed quarto equation employs the method of undetermined coefficients. 笛卡儿的分解四次方程的解法采用待定系数。
