The first one is incorrect because (4x)^2 is the same as 4x^2 and not 8x^2.
2(4x)^2=8x^2 would however, be right.
The second one is incorrect because a number squared can never be negative as a negative* a negative is always a positive, a correct answer would be: 3^2=9
The third one is incorrect because 6/12=0.5 not 2, a correct answer would be:
12x^8/6x^4=2x^4
Hope this helps :)
