Solution - Simplification or other simple results

Step  1  :

Trying to factor by splitting the middle term

 1.1     Factoring  c²-6c-72 

The first term is,  c²  its coefficient is  1 .
The middle term is,  -6c  its coefficient is  -6 .
The last term, "the constant", is  -72 

Step-1 : Multiply the coefficient of the first term by the constant   1 • -72 = -72 

Step-2 : Find two factors of  -72  whose sum equals the coefficient of the middle term, which is   -6 .

Step-3 : Rewrite the polynomial splitting the middle term using the two factors found in step 2 above,  -12  and  6 
                     c² - 12c + 6c - 72

Step-4 : Add up the first 2 terms, pulling out like factors :
                    c • (c-12)
              Add up the last 2 terms, pulling out common factors :
                    6 • (c-12)
Step-5 : Add up the four terms of step 4 :
                    (c+6)  •  (c-12)
             Which is the desired factorization

Final result :

  (c + 6) • (c - 12)