How to express mathematics? 1. Emphasizing = extra force given to a word or words, especially to show that it is important. --Material emphasizing the second-order linear equation has been inserted at appropriate place in next chapter.-- 2. Appendix = section giving extra information at the end of book. --An appendix present, without proof, the fundamental of second and third order determinant.--

3. Ordinary = normal, usual. --A differential equation involving ordinary derivatives of one or more dependent variable with respect to single independent variable is called an ordinary differential equation.-- 4. Boundary = line that marks a limit. --Once the boundary canditions are established, a variational formulation in the finite domain will be provided.--