a) x^3 - 7x - 6
= x^3 - x - 6x - 6
= x(x^2 - 1 ) - 6 (x + 1 )
= x(x-1)(x+1) - 6 ( x + 1 )
= ( x+ 1 ) [ x(x-1) - 6 ]
= ( x + 1 )(x^2 - x - 6 )
= ( x+ 1 ) ( x^2 - 3x + 2x - 6 )
= ( x+ 1 ) [ x(x-3) + 2 ( x- 3 )]
=(x+1)(x+2)(x-3)
b) x^3 - x^2 - 14x + 24
= x^3 - 3x^2 + 2x^2 - 6x - 8x + 24
= x^2 ( x - 3 ) + 2x(x-3) - 8 ( x- 3 )
= ( x - 3 )( x^2 + 2 x - 8 )
= ( x- 3 ) [ x^2 + 4x - 2x - 8 )]
= ( x- 3 )( [ x( x + 4 ) - 2 ( x+ 4) ]
= ( x - 3 )( x+ 4 )( x- 2 )
c) x^5 + x + 1
= x^5 - x^2 + x^2 + x + 1
= x^2(x^3 - 1 ) + x^2 + x + 1
= x^2 ( x- 1 )(x^2 + x + 1 ) + x^2 + x+ 1
= ( x^2 + x + 1 )( x^3 - x^2 ) + x^2 + x + 1
=( x^2 + x + 1 )( X^3 - x^2 + 1 )
x2+7x+6
giúp mình nha (phân tích thành nhân tử )
nhanh mình k cho
\(x^8+x^7+1\)
\(=\left(x^8-x^6+x^5-x^3+x^2\right)+\left(x^7-x^5+x^4-x^2+x\right)+\left(x^6-x^4+x^3-x+1\right)\)
\(=x^2\left(x^6-x^4+x^3-x+1\right)+x\left(x^6-x^4+x^3-x+1\right)+\left(x^6-x^4+x^3-x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^6-x^4+x^3-x+1\right)\)
\(x^5+x+1\)
\(=x^5-x^4+x^2+x^4-x^3+x+x^3-x^2+1\)
\(=x^2\left(x^3-x^2+1\right)+x\left(x^3-x^2+1\right)+\left(x^3-x^2+1\right)\)
\(=\left(x^2+x+1\right)\left(x^3-x^2+1\right)\)
