Solution - Simplification or other simple results

Step  1  :

Equation at the end of step  1  :

  (23x2 -  14x) -  15

Step  2  :

Trying to factor by splitting the middle term

 2.1     Factoring  8x²-14x-15 

The first term is,  8x²  its coefficient is  8 .
The middle term is,  -14x  its coefficient is  -14 .
The last term, "the constant", is  -15 

Step-1 : Multiply the coefficient of the first term by the constant   8 • -15 = -120 

Step-2 : Find two factors of  -120  whose sum equals the coefficient of the middle term, which is   -14 .

Step-3 : Rewrite the polynomial splitting the middle term using the two factors found in step 2 above,  -20  and  6 
                     8x² - 20x + 6x - 15

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

Final result :

  (2x - 5) • (4x + 3)