Expression 5: "f" Subscript, "d" , Baseline left parenthesis, "x" , right parenthesis equals left brace, "a" less than or equal to "x" less than or equal to "b" : StartFraction, "d" Over "d" "x" , EndFraction "f" left parenthesis, "x" , right parenthesis , right bracefdx=a≤x≤b:ddxfx