運算式 4: "k" equals left bracket, 0 , 1... "N" , right bracketk=0,1...N
4
運算式 5: StartFraction, 3 "k" Over "N" , EndFraction left brace, "f" left parenthesis, "x" , right parenthesis greater than StartFraction, 3 "k" Over "N" , EndFraction , right brace left brace, "f" left parenthesis, "x" , right parenthesis less than or equal to StartFraction, 3 "k" plus 3 Over "N" , EndFraction , right brace3kNfx>3kNfx≤3k+3N
5
運算式 6: StartFraction, 3 "k" Over "N" , EndFraction less than or equal to "y" less than or equal to StartFraction, 3 "k" plus 3 Over "N" , EndFraction left brace, "f" left parenthesis, "x" , right parenthesis greater than or equal to StartFraction, left parenthesis, 3 "k" plus 3 , right parenthesis Over "N" , EndFraction , right brace3kN≤y≤3k+3Nfx≥3k+3N
