x⁴ - 4x³ - 8x² + 8x 

 = x(x³ - 4x² - 8x + 8) 

= x[x³ + 8 - 4x(x + 2)] 

= x[(x + 2)(x² - 2x + 4) - 4x(x + 2)] 

= x(x + 2)(x² - 6x + 4)

= x(x + 2)(x² - 6x + 9 - 5) 

 = \(x\left(x+2\right)\left[\left(x-3\right)^2-5\right]=x\left(x+2\right)\left(x-3+\sqrt{5}\right)\left(x-3-\sqrt{5}\right)\)

\(x^4-4x^3-8x^2+8x\)

\(=x\left(x^3-4x^2-8x+8\right)\)

\(=x\left(x^3-6x^2+2x^2+4x-12x+8\right)\)

\(=x\left[\left(x^3-6x^2+4x\right)+\left(2x^2-12x+8\right)\right]\)

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

\(=x\left(x^2-6x+4\right)\left(x+2\right)\)

\(=x\left[\left(x-3\right)^2-\left(\sqrt{5}\right)^2\right]\left(x+2\right)\)

\(=x\left(x-3-\sqrt{5}\right)\left(x-3+\sqrt{5}\right)\left(x+2\right)\)

\(4x^4+2x^3-8x^2+3x+9\)

\(=4x^4+4x^3-2x^3-2x^2-6x^2-6x+9x+9\)

\(=\left(x+1\right)\left(4x^3-2x^2-6x+9\right)\)

\(=\left(x+1\right)\left(4x^3+6x^2-8x^2-12x+6x+9\right)\)

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

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

THAM KHẢO

\(x^3-x^2-4x^2+8x-4\)

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

\(=x\left(x^2-4x+4\right)-\left(x^2-4x+4\right)\)

\(=\left(x-1\right)\left(x^2-4x+4\right)\)

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

x⁴+8x³+15x²-4x-2

= (x⁴+4x³+x²)+(4x³+16x²+4x)-(2x²+8x+2)

= x².(x²+4x+1)+4x.(x²+4x+1) -2(x²+4x+1)

= (x²+4x+1).(x²+4x-2)

ai h minh minh h lai cho

a: =(2x-3y)^2-4(2x-3y)

=(2x-3y)(2x-3y-4)

b: =3x^2+21x-x-7

=(x+7)(3x-1)

c: =(3x-1)^4+2(3x-1)^2+1

=[(3x-1)^2+1]^2

d: =2x^3-2x^2-x^2+x+x-1

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