Hello, please consider the following.
[tex]\begin{aligned}1280x^{11}-405x^7&=5x^7(256x^4-81)\\\\&= 5x^7(16^2(x^2)^2-9^2)\\\\&=5x^7(16x^2-9)(16x^2+9)\\\\&=5x^7((4x)^2-3^2)(16x^2+9)\\\\&\large \boxed{=5x^7(4x-3)(4x+3)(16x^2+9)}\end{aligned}[/tex]
So, the last one is the correct answer.
Thank you.
