Answer:
[tex]\large\boxed{9y^2-(1+2y)^2=(y-1)(5y+1)}[/tex]
Step-by-step explanation:
[tex]9y^2-(1+2y)^2=3^2y^2-(1+2y)^2=(3y)^2-(1+2y)^2\\\\\text{use}\ a^2-b^2=(a-b)(a+b)\\\\=(3y-(1+2y))(3y+(1+2y))=(3y-1-2y)(3y+1+2y)\\\\\text{combine like terms}\\\\=(y-1)(5y+1)[/tex]
