we are given
[tex] (5x + 1)(5x - 1) [/tex]
we can distribute it
[tex] 5x*5x-1*5x+1*5x-1*1 [/tex]
[tex] 25x^2-5x+5x-1 [/tex]
now, we can simplify it
[tex] 25x^2-1 [/tex]...............Answer