As I am completely brand new to this subject/branch of mathematics, please explain thoroughly, step by step on how to complete this This is a practice from my ACT prep guide take your time, as there is no rush *Ignore the last answer option

Remember that
The difference of squares is of the form
[tex](a+b)(a-b)=a^2-b^2[/tex]In this problem we have
[tex](3x-4y^2)(3x+4y^2)[/tex]so
a=3x
b=4y^2
therefore
Apply the difference of squares
[tex](3x-4y^2)(3x+4y^2)=(3x)^2-(4y^2)^2=9x^2-16y^4[/tex]