a) (x - 1)(x - 2).                        b) 4(x - 2)(x - 7).

c) (x + 2)(2x +1).                    d) (x - l)(2x - 7).

e) (2x + 3y - 3)(2x - 3y +1).    g) (x - 3)( x 3   +   x 2  - x +1).

h) (x + y)(x + y-l)(x + y + l).

a) 9x⁴+16y⁶-24x²y³

=(3x²)²-2.3x².4y³+(4y³)²

=(3x²-4y³)²

b) 16x²-24xy+9y²

=(4x)²-2.4x.3y+(3y)²

=(4x-3y)²

c) 36x²-(3x-2)²

=(36x-3x+2)(36x+3x-2)

=(33x+2)(39x-2)

d) 27x³+54x²y+36xy²+8y³

=(3x)³+3.(3x)².2y+3.3x.(2y)²+(2y)³

=(3x+2y)³

e) y⁹-9x²y⁶+27x⁴y³-27x⁶

=(y³)³-3.(y³)².3x²+3.y³.(3x²)²-(3x²)³

=(y³-3x²)³

f) 64x³+1

= (4x)³+1³

=(4x+1)[(4x)²-4x.1+1²]

=(4x+1)(16x²-4x+1)

e) 27x⁶-8x³  *sửa đề*

=(3x²)³-(2x)³

=(3x²-2x)[(3x)²+3x².2x+(2x)²]

=(3x²-2x)(9x²+6x³+4x²)

~~~

Đúng hết mà?

1: \(6x^2y-9xy^2+3xy\)

\(=3xy\left(2x-3y+1\right)\)

2: \(\left(4-x\right)^2-16\)

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

\(=-x\cdot\left(8-x\right)\)

3: \(x^3+9x^2-4x-36\)

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

\(=\left(x+9\right)\left(x-2\right)\left(x+2\right)\)

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

2) \(\left(4-x\right)^2-16=\left(4-x\right)^2-4^2=\left(4-x-4\right)\left(4-x+4\right)=-x\left(8-x\right)\)

3) \(x^3+9x^2-4x-36\\ =\left(x^3-2x^2\right)+\left(11x^2-22x\right)+\left(18x-36\right)\\ =x^2\left(x-2\right)+11x\left(x-2\right)+18\left(x-2\right)\\ =\left(x^2+11x+18\right)\left(x-2\right)\\ =\left[\left(x^2+2x\right)+\left(9x+18\right)\right]\left(x-2\right)\\ =\left[x\left(x+2\right)+9\left(x+2\right)\right]\left(x-2\right)\\ =\left(x+2\right)\left(x+9\right)\left(x-2\right)\)

x⁴ - 9x³ + 28x² - 36x + 16

Thử với x = 4 ta có :

4⁴ - 9.4³ + 28.4² - 36.4 + 16 = 0

Vậy 4 là nghiệm của đa thức . Theo hệ quả của định lí Bézout thì đa thức trên chia hết cho x - 4

Thực hiện phép chia đa thức cho x - 4 ta được x³ - 5x² + 8x - 4

Vậy ta phân tích được ( x - 4 )( x³ - 5x² + 8x - 4 )

Tiếp tục : Thử x = 2 với x³ - 5x² + 8x - 4

Ta có : 2³ - 5.2² + 8.2 - 4 = 0 

Vậy 2 là nghiệm của đa thức . Theo hệ quả của định lí Bézout thì x³ - 5x² + 8x - 4 chia hết cho x - 2

Thực hiện phép chia  x³ - 5x² + 8x - 4 cho x - 2 ta được x² - 3x + 2

Vậy ta phân tích được ( x - 4 )( x - 2 )( x² - 3x + 2 )

x² - 3x + 2 = x² - x - 2x + 2 

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

                  = ( x - 2 )( x - 1 )

Vậy : x⁴ - 9x³ + 28x² - 36x + 16 = ( x - 4 )( x - 2 )( x - 2 )( x - 1 ) = ( x - 4 )( x - 2 )²( x - 1 )

a. \(x^4-9x^3+28x^2-36x+16\)

\(=x^4-8x^3+20x^2-16x-x^3+8x^2-20x+16\)

\(=x\left(x^3-8x^2+20x-16\right)-\left(x^3-8x^2+20x-16\right)\)

\(=\left(x-1\right)\left(x^3-8x^2+20x-16\right)\)

\(=\left(x-1\right)\left(x^3-6x^2+8x-2x^2+12x-16\right)\)

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

\(=\left(x-1\right)\left(x-2\right)\left(x^2-6x+8\right)\)

\(=\left(x-1\right)\left(x-2\right)\left(x^2-2x-4x+8\right)\)

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

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

A, \(x^3-4x^2-9x+36=x^2\left(x-4\right)-9\left(x-4\right)\)

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

\(b,x^2-y^2-2x-2y=\left(x-y\right)\left(x+y\right)-2\left(x+y\right)\)

\(=\left(x+y\right)\left(x-y-2\right)\)

\(12y-9x^2+36-3x^2y\)

\(=\left(36-9x^2\right)-\left(3x^2y-12y\right)\)

\(=-9\left(x^2-4\right)-3y\left(x^2-4\right)\)

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

\(12y-9x^2+36-3x^2y\)

\(=\left(12y-3x^2y\right)-\left(9x^2-36\right)\)

\(=3y\left(4-x^2\right)-9\left(x^2-4\right)\)

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

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

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

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

=(−3)(x−2)(x+2)(3+y)

Lời giải:
\(x^3(x^2-7)^2-36x=x[x^2(x^2-7)^2-36]\\ =x[(x^3-7x)^2-6^2]=x(x^3-7x-6)(x^3-7x+6)\\ =x[x^2(x-3)+3x(x-3)+2(x-3)][x^2(x-2)+2x(x-2)-3(x-2)]\\ =x(x-3)(x^2+3x+2)(x-2)(x^2+2x-3)\\ =x(x-3)(x+1)(x+2)(x-2)(x-1)(x+3)\)

3) \(x^2\left(x+2y\right)-x-2y\)

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

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

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

4) \(x^3-4x^2-9x+36\)

\(=\left(x^3-4x^2\right)-\left(9x-36\right)\)

\(=x^2\cdot\left(x-4\right)-9\left(x-4\right)\)

\(=\left(x-4\right)\left(x^2-9\right)\)

\(=\left(x-4\right)\left(x+3\right)\left(x-3\right)\)

\(x^2\left(x+2y\right)-x-2y\\ =x^2\left(x+2y\right)-\left(x+2y\right)\\ =\left(x^2-1\right)\left(x+2y\right)\\ =\left(x-1\right)\left(x+1\right)\left(x+2y\right)\\ ---\\ x^3-4x^2-9x+36\\ =x^2\left(x-4\right)-9\left(x-4\right)\\ =\left(x^2-9\right)\left(x-4\right)\\ =\left(x-3\right)\left(x+3\right)\left(x-4\right)\)