\(=x^2+x+6x+6\)

\(=x.\left(x+1\right)+6.\left(x+1\right)\)

\(=\left(x+1\right).\left(x+6\right)\)

Ta có `:`

`x^3 - 7x-6`

`= x^3 - 9x + 2x - 6`

`= x( x^2 - 9 ) + 2( x-3 )`

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

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

`= ( x^2 + 3x + 2 )( x-3 )`

`= ( x^2 + 2x + x + 2 )( x-3 )`

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

`= ( x+1)(x+2)(x-3)`  

hãy giúp mình đi ạ `bb!` 

Đề đúng không bạn ? 

đề chuẩn đến vi khuẩn cũng phải gật gù đó pn

THAM KHẢO NHÉ BẠN, MÌNH KO VT ĐC TRONG NÀY NÊN PHẢI RA WORD VÍT R COPY VÀO Á:

$7x^2-13x+6=0\iff 7x^2-7x-6x+6=0$

$\iff 7x\left(x-1\right)-6\left(x-1\right)=0\iff \left(7x-6\right)\left(x-1\right)=0$

$\iff \{\begin{array}{c}x-1=0\\ 7x-6=0\end{array}$ $\iff \{\begin{array}{c}x=1\\ 7x=6\end{array}$ $\iff \{\begin{array}{c}x=1\\ x=\frac{6}{7}\end{array}$ vậy $x=1;x=\frac{6}{7}$

`#040911`

`7x^2 - 13x + 6`

`= 7x^2 - 7x - 6x + 6`

`= (7x^2 - 7x) - (6x - 6)`

`= 7x(x - 1) - 6(x - 1)`

`= (7x - 6)(x - 1)`

x³ + 7x - 6

= x³ - x - 6x - 6

= x³ - x - 6 (x+1)

= x (x² - 1) - 6 (x+1)

= (x + 1) ( x (x - 1) - 6 )

= ( x + 1) ((x² - x - 6))

= (x + 1) ((x² + 2 - 3 - 6))

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

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

Ta có: (x - 1)(2x² - 7x) + 6

      =  2x³ - 9x² + 7x + 6

      =  2x³ - 4x² - 5x² + 10x - 3x + 6

      = 2x²(x - 2) - 5x(x - 2) - 3(x - 2)

      = (x - 2)(2x² - 5x - 3)

      = (x - 2)(2x² - 6x + x - 3)

      = (x - 2)[2x(x - 3) + x - 3]

      = (x - 2)(x - 3)(2x + 1)

a) x³ - 7x - 6 = x³ + x² - x² - x - 6x - 6

= x²(x + 1) - x(x + 1) - 6(x + 1)

= (x + 1)(x² - x - 6)

= (x + 1)(x² + 2x - 3x - 6)

= (x + 1)[x(x + 2) - 3(x + 2)]

= (x + 1)(x + 2)(x - 3)

\(x^3-7x-6\)

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

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

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

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

\(=\left(x+2\right)\left[x\left(x+1\right)-3\left(x+1\right)\right]\)

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