prove the polynomial identity

Answer:
The steps have been shown in the solution below
Step-by-step explanation:
[tex](3x+1)^{2} - 2(3x+1)=(3x+1)(3x-1)[/tex]
[tex]9x^{2} +6x+1 -6x-2= (3x+1) (3x-1)\\\\9x^{2} -1=(3x+1)(3x-1)\\\\(3x+1)(3x-1)=(3x+1)(3x-1)\\[/tex]
LHS=RHS Hence, proved.