Module 4: Systems of Equations and Equations of Order Greater Than One
  Lecture 13: Direct Methods For Higher Order Equations
 

 

Substituting (4.7) into (4.6), we get

(4.8)

If and , (4.8) will agree with the first four terms of the Taylor's series expansion of . The term in will not match the fifth term in the Taylor's series for any choice of and . Similarly, if and then agrees with to order . Thus, one solution is

(4.9)