表达式5: "F" left parenthesis, "x" , right parenthesis equals "f" left parenthesis, StartFraction, "x" Over 3.6 , EndFraction , right parenthesisFx=fx3.6
5
表达式6: StartFraction, "d" Over "d" "x" , EndFraction "F" left parenthesis, "x" , right parenthesis equals 0.ddxFx=0.