x³ - 6x² - x + 30

= (x + 2).x² - 6x² - x + 30/x + 2

= x² - 8x + 15

= (x + 2)(x - 3)(x - 5)

\(x^3-6x^2-x+30\)

\(=\left(x^3-8x^2+15x\right)+\left(2x^2-16x+30\right)\)

\(=x\left(x^2-8x+15\right)+2\left(x^2-9x+15\right)\)

\(=\left(x^2-8x+15\right)\left(x+2\right)\)

\(=\left(x^2-3x-5x+15\right)\left(x+2\right)\)

\(=\left[x\left(x-3\right)-5\left(x-3\right)\right]\left(x+2\right)\)

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

\(\Leftrightarrow x^3-3x^2-3x^2+9x-10x+30\)

\(\Leftrightarrow x^2\left(x-3\right)-3x\left(x-3\right)-10\left(x-3\right)\)

\(\Leftrightarrow\left(x-3\right)\left(x^2-3x-10\right)\)

\(\Leftrightarrow\left(x-3\right)\left(x-5\right)\left(x+2\right)\)

\(=\left(x^3-2x^2\right)+\left(8x^2-16x\right)+\left(15x-30\right)\)

\(=x^2\left(x-2\right)+8x\left(x-2\right)+15\left(x-2\right)\)

\(=\left(x-2\right)\left(x^2+8x+15\right)\)

\(=\left(x-2\right)\left(x^2+3x+5x+15\right)\)

\(=\left(x-2\right)\left[x\left(x+3\right)+5\left(x+3\right)\right]\)

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

x³-6x²-x+30

=x³-5x²-x²+5x-6x+30

=(x-5)(x²-x-6)

=(x-5)(x-3)(x+2)

\(x^3-6x^2-x+30=x^3-3x^2-3x^2+9x-10x+30.\)

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

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

\(=\left(x-3\right)\left(x^2+2x-5x-10\right)\)

\(=\left(x-3\right)\left[x\left(x+2\right)-5\left(x+2\right)\right]\)

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

Vậy \(x^3-6x^2-x+30=\left(x-3\right)\left(x+2\right)\left(x-5\right)\) 

cái này bạn hỏi rồi mà mk đã tl rồi đó bạn ấn vô câu hỏi của tôi rồi kéo xuống mà xem

a) x³ - 7x + 6

= x³ - 2x² + 2x² - 4x - 3x + 6

= x² ( x - 2 ) + 2x ( x - 2 ) - 3 ( x - 2 )

= ( x - 2 ) ( x² + 2x - 3 )

= ( x - 2 ) ( x² - x + 3x - 3 )

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

= ( x - 2 ) ( x - 1 ) ( x + 3 )

b ) x³ - 9x² + 6x + 16

= x³ - 8x² - x² + 8x - 2x + 16

= x² ( x - 8 ) - x ( x - 8 ) - 2 ( x - 8 )

= ( x - 8 ) ( x² - x - 2 )

= ( x - 8 ) ( x² + x - 2x - 2 )

= ( x - 8 ) [ x ( x + 1 ) - 2 ( x + 1 ) ]

= ( x - 8 ) ( x + 1 ) ( x - 2 )

c ) x³ - 6x² - x + 30

= x³ - 5x² - x² + 5x - 6x + 30

= x² ( x - 5 ) - x ( x - 5 ) - 6 ( x - 5 )

= ( x - 5 ) ( x² - x - 6 )

= ( x - 5 ) ( x² - 3x + 2x - 6 )

= ( x - 5 ) [ x ( x - 3 ) + 2 ( x - 3 ) ]

= ( x - 5 ) ( x - 3 ) ( x + 2 )

d ) 2x³ - x² + 5x + 3

= 2x³ + x² - 2x² - x + 6x + 3

= x² ( 2x + 1 ) - x ( 2x + 1 ) + 3 ( 2x + 1 )

= ( 2x + 1 ) ( x² - x + 3 )

^{\(^{x^3-6x^2-x+30=x^3-5x^2-3x^2+15x-2x^2-10x-6x+30}\)}

=x^2(x-5)-3x(x-5)-2x(x-5)-6(x-5)

=(x-5)(x^2-3x-2x-6)

=(x-5)[x(x-3)-2(x-3)]

=(x-5)(x-3)(x-2)

\(x^3-6x^2-x+30\) 

= \(x^3-5x^2-3x^2+15x+2x^2-10x-6x+30\)

= \(x^2\left(x-5\right)-3x\left(x-5\right)+2x\left(x-5\right)-6\left(x-5\right)\)

= \(\left(x-5\right)\left(x^2-3x+2x-6\right)\)

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

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

a)\(=x^3+2x^2-8x^2-16x+15x+30\)

\(=x^2\left(x+2\right)-8x\left(x+2\right)+15\left(x+2\right)\)

\(=\left(x+2\right)\left(x^2-8x+15\right)\)

\(=\left(x+2\right)\left(x^2-5x-3x+15\right)\)

\(=\left(x+2\right)\left[x\left(x-5\right)-3\left(x-5\right)\right]\)

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

nha

a) bt \(=\left(x-8\right)\left(x^2-x-2\right)=\left(x-8\right)\left(x+1\right)\left(x-2\right)\)

kl: ...

b) \(=\left(x+2\right)\left(x^2-8x-15\right)=\left(x+2\right)\left(x-5\right)\left(x-3\right)\)

kl:....

a, \(x^3-9x^2+6x+16\)

\(=x^3-8x^2-x^2+8x-2x+16\)

\(=x^2\left(x-8\right)-x\left(x-8\right)-2\left(x-8\right)\)

\(=\left(x-8\right)\left(x^2-x-2\right)\)

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

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

\(=\left(x-8\right)\left(x-2\right)\left(x+1\right)\)

b, \(x^3-6x^2-x+30\)

\(=x^3-5x^2-x^2+5x-6x+30\)

\(=x^2\left(x-5\right)-x\left(x-5\right)-6\left(x-5\right)\)

\(=\left(x-5\right)\left(x^2-x-6\right)\)

\(=\left(x-5\right)\left(x^2-3x+2x-6\right)\)

\(=\left(x-5\right)\left[x\left(x-3\right)+2\left(x-3\right)\right]\)

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

Chúc bạn học tốt!!!