Lời giải:
$-4x^4+1+2x^2y-y=-(4x^4-1)+(2x^2y-y)$

$=-(2x^2-1)(2x^2+1)+y(2x^2-1)$

$=(2x^2-1)[-(2x^2+1)+y]$

$=(2x^2-1)(y-2x^2-1)$

\(x^4+4x^3+2x^2-4x+1\)

\(=x^4+2x^3-x^2+2x^3+4x^2-2x-x^2-2x+1\)

\(=x^2\left(x^2+2x-1\right)+2x\left(x^2+2x-1\right)-\left(x^2+2x-1\right)\)

\(=\left(x^2+2x-1\right)^2\)

\(4x^4-8x^3+4x^3-8x^2+x^2-2x-2x+4\\ =4x^3\left(x-2\right)+4x^2\left(x-2\right)+x\left(x-2\right)-2\left(x-2\right)\\ =\left(x-2\right)\left(4x^3+4x^2+x-2\right)\\ =\left(x-2\right)\left(4x^3-2x^2+6x^2-3x+4x-2\right)\\ =\left(x-2\right)\left[2x^2\left(2x-1\right)+3x\left(2x-1\right)+2\left(2x-1\right)\right]\\ =\left(x-2\right)\left(2x-1\right)\left(2x^2+3x-2\right)\)

=[(x^2)^2-2.2x.1+1]-2

=(x^2-1)^2-2

=[(x-1).(x+1)]^2-2

Nếu đúng thì mong bạn clik hộ cái nha

x⁴ - 4x - 1 = x⁴ -2x² + 1 - 2x² +4x - 2

               = (x^{2 -} 1)² - 2(x - 1)²

               = ... Tự làm tiếp nhé