Solution - Simplification or other simple results

Step  1  :

Equation at the end of step  1  :

  (2•3d2) -  21d

Step  2  :

Step  3  :

Pulling out like terms :

 3.1     Pull out like factors :

   6d² - 21d  =   3d • (2d - 7) 

Final result :

  3d • (2d - 7)