Solution - Simplification or other simple results

Reformatting the input :

Changes made to your input should not affect the solution:

 (1): "a1"   was replaced by   "a^1". 

Step  1  :

Step  2  :

Pulling out like terms :

 2.1     Pull out like factors :

   a² - a  =   a • (a - 1) 

Final result :

  a • (a - 1)