수식 2: "y" equals "f" left parenthesis, "f" left parenthesis, "x" , right parenthesis , right parenthesisy=ffx
2
수식 3: "y" equals "f" left parenthesis, "f" left parenthesis, "f" left parenthesis, "x" , right parenthesis , right parenthesis , right parenthesisy=fffx