[(x-1)(x+1)-(2x+1)(2x-1)]^2-(3x^2)^2-12x^2+2=
[(x-1)(x+1)-(2x+1)(2x-1)]^2-(3x^2)^2-12x^2+2=
$[(x-1)(x+1)-(2x+1)(2x-1)]^2-(3x^2)^2-12x^2+2$ =
= $[x^2-1-(4x^2-1)]^2-9x^{2·2}-12x^2+2$ =
= $ [x^2-1-4x^2+1]^2-9x^4-12x^2+2$ =
= $[-3x^2]^2-9x^4-12x^2+2$ =
= $9x^4-9x^4-12x^2+2$ =
= $-12x^2+2$
o anche:
$-2(6x^2-1)$.