9x^2 - 4 = (3x - 2) (3x + 2)
x^2 + 9 + 20 = (x + 5) (x + 4)
3x^2 + 5x + 2 = (3x +2) (x +1)
x^2 + 5x + 4 = (x +4) (x + 1)
x^2 + 3x - 10 = (x + 5) (x - 2)
x^2 + x - 6 = (x +3) (x - 2)
then substitute : (3x - 2) (3x + 2)
--------------------
(x + 5) (x + 4) (x + 5) (x -2)
-------------------------------- . -------------------
(3x + 2) (x + 1) (x +3) (x -2)
--------------------
(x + 4) (x + 1)
then:
(3x - 2) (3x + 2) (x + 4) (x + 1) (x + 5) (x -2)
---------------------- ------------------- ------------------
(x + 5) (x + 4) (3x + 2) (x + 1) (x +3) (x -2)
then cancel all the equation that is thesame at the numerator and demonitor
(3x + 2) , (x + 5) , (x + 4) , (x + 1) and (x - 2)
(3x - 2)
then what is left is ------------
(x +3)