\(3x^4-48=3\left(x^4-16\right)=3\left[\left(x^2\right)^2-4^2\right]\\ =3\left(x^2-4\right)\left(x^2+4\right)\\ =3\left(x-2\right)\left(x+2\right)\left(x^2+4\right)\)

\(\left(x^2+6x\right)\left(x^2+14x+40\right)+128\)

\(=\left(x^2+6x\right)\left(x^2+14x+40\right)\)

\(=x^4+20x^3+124x^2+240x\)

\(=x^4+20x^3+124x^2+240x+128\)

\(\left(x^2+6x\right)\left(x^2+14x+40\right)+128\)

\(=x^4+14x^3+40x^2+6x^3+84x^2+240x+128\)

\(=x^4+20x^3+124x^2+240x+128\)

mk chỉ biết đến đây thôi

Ta có

a,    x²-x-y²-y

=x²-y²-(x+y)

=(x-y)(x+y) - (x+y)

=(x+y)(x-y-1)

b,   x²-2xy+y²-z²

=(x-y)²-z²

=(x-y-z)(x-y+z)

con bai 32, 33 neu ban tra loi duoc minh h them

nhanh nha

\(3x^4-48\)

\(=\left(3x^4-6x^3\right)+\left(6x^3-12x^2\right)+\left(12x^2-24x\right)+\left(24x-48\right)\)

\(=3x^3\left(x-2\right)+6x^2\left(x-2\right)+12x\left(x-2\right)+24\left(x-2\right)\)

\(=\left(x-2\right)\left[\left(3x^3+6x^2\right)+\left(12x+24\right)\right]\)

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

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

\(x^4-8x\)

\(=x\left(x^3-8\right)\)

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

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

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

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

\(=\left(x^3-3x^2\right)-\left(3x^2-9x\right)\)

\(=x^2\left(x-3\right)-3x\left(x-3\right)\)

\(=\left(x-3\right)\left(x^2-3x\right)\)

\(=x\left(x-3\right)\left(x-3\right)\)

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

\(=\left(x^2+x\right)^2+3\left(x^2+x\right)-10\)

\(=\left(x^2+x+5\right)\left(x^2+x-2\right)\)

\(=\left(x^2+x+5\right)\left(x+2\right)\left(x-1\right)\)

x^2 + 7x -15

= x^2 + 7x +12,25  -27,25

= (x+3,5)^2 - 27, 25

= ( x+3,5 - \(\sqrt{27,25}\))(x+3,5+\(\sqrt{27,25}\))

x^2-4+4xy-8y=x^2+4xy+4y^2-4y^2-8y-4=(x+2y)^2-(2y+2)^2=(x+2y-2y+2)(x+2y+2y-2)=(x+2)(x+4y-2)