Expresión 28: "s" left parenthesis, "x" , right parenthesis equals left parenthesis, "a" Subscript, 4 , Baseline minus "a" Subscript, 3 , Baseline , right parenthesis "x" squared plus left parenthesis, "b" Subscript, 4 , Baseline minus "b" Subscript, 3 , Baseline , right parenthesis "x" plus left parenthesis, "c" Subscript, 4 , Baseline minus "c" Subscript, 3 , Baseline , right parenthesissx=a4−a3x2+b4−b3x+c4−c3