Expression 11: "f" left parenthesis, "x" , right parenthesis equals "g" left parenthesis, "x" , right parenthesis plus "x" left brace, "x" greater than or equal to 0 , right bracefx=gx+xx≥0
11
Expression 12: polygon left parenthesis, "A" , "B" , "C" , right parenthesispolygonA,B,C
12
Expression 13: polygon left parenthesis, "C" , "O" , right parenthesispolygonC,O