Solution - Simplification or other simple results

Step  1  :

Equation at the end of step  1  :

  (2x2 +  x) -  21

Step  2  :

Trying to factor by splitting the middle term

 2.1     Factoring  2x²+x-21 

The first term is,  2x²  its coefficient is  2 .
The middle term is,  +x  its coefficient is  1 .
The last term, "the constant", is  -21 

Step-1 : Multiply the coefficient of the first term by the constant   2 • -21 = -42 

Step-2 : Find two factors of  -42  whose sum equals the coefficient of the middle term, which is   1 .

Step-3 : Rewrite the polynomial splitting the middle term using the two factors found in step 2 above,  -6  and  7 
                     2x² - 6x + 7x - 21

Step-4 : Add up the first 2 terms, pulling out like factors :
                    2x • (x-3)
              Add up the last 2 terms, pulling out common factors :
                    7 • (x-3)
Step-5 : Add up the four terms of step 4 :
                    (2x+7)  •  (x-3)
             Which is the desired factorization

Final result :

  (x - 3) • (2x + 7)