運算式 7: "A" equals Start integral from "a" to "b" , end integral, "f" left parenthesis, "x" , right parenthesis "d" "x"A=∫bafxdx
7
運算式 8: 0 less than or equal to "y" less than or equal to "f" left parenthesis, "x" , right parenthesis left brace, "a" less than or equal to "x" less than or equal to "b" , right brace0≤y≤fxa≤x≤b
