$=x^4(x^4+4x^3+8x^2-4x+1)-4x^3(x^4+4x^3+8x^2-4x+1)+8x^2(x^4+4x^3+8x^2-4x+1)+4x(x^4+4x^3+8x^2-4x+1)+x^4+4x^3+8x^2-4x+1$$=(x^4+4x^3+8x^2-4x+1)(x^4-4x^3+8x^2+4x+1)$
$=(x^
8+
2x^4+1)
+96x^
4=(x^4+
1)^2+1
6x^2(x^4+
1)+64x^
4-16x^2
(x^4+1)+
32x^4
$$=(x^4+
8x^
2+
1)^2-1
6x^
2(x^
4-2x^2+1
)=(x^4+8x^2+1)^
2-
(4x^3
-4x
)^2$
tự làm tiếp nha e