L4_A
      6.6 Product Rule and Gradient
           (1)Theorem (微分的四則運算)
   

L4_B
      6.6 Product Rule and Gradient (cont.)
           (1)Theorem (微分的四則運算)(cont.)


L4_C
       6.6 Procluct Rule and Gradient (cont.)
              (1)Cor: 微分的除法  
       6.7 Mean-value thm
              (1)Definiton

              (2)Theorem: (Mean-value thm)

L4_D
      6.7 Mean-value thm (cont.)
            (1)Theorem: (Mean-value thm)(cont.)
            (2)Theorem