You can put this solution on YOUR website! (-4n)^2 = (-4)(-4)=(16) square n =n^2. So one has (16n^2). Next,
(3n^7)^2 = (3)(3)= (9) multiply your powers, ^7x^2=^14. So one has (9n^14). Next, put them together and multiply.
(16n^2)(9n^14)
16x9=144 and add powers 2^+14^=^16
answer= 144n^16
(-4n)^2(3n^7)^2
(16n^2)(9n^14)
144n^16