-(a² + b²)         |x| - (1 + 2)         √(1 + 2) / (3 + 4)
 

        |-| 
         |  
         | 
        |+| 
       /   \  
      /     \ 
   |^|       |^|
  /   \     /   \
 /     \   /     \ 
a       2 b       2
  

     |-|
    /   \
   /     \ 
|abs|     |+|
  |      /   \
  |     /     \ 
  x    1       2
  

       |/| 
      /   \  
     /     \ 
  |√|       |+|
   |       /   \
   |      /     \ 
  |+|    3       4
 /   \   
1     2