Ta có: \(1+6x-6x^2-x^3\)
\(=-x^3-6x^2+6x+1\)
\(=\left(-x^3+1\right)-6x\left(x-1\right)\)
\(=-\left(x-1\right)\left(x^2+x+1\right)-6x\cdot\left(x-1\right)\)
\(=\left(x-1\right)\left(-x^2-x-1-6x\right)\)
\(=-\left(x-1\right)\left(x^2+7x+1\right)\)
\(1+6x-6x^2-x^3\)
= (1-x^3)+(6x-6x^2)
=(1-x)(1+x+x^2)+6x(1-x)
=(1-x)( 1+ x+ x^2 + 6x)
=(1-x)(1+x^2 +7x)
Đây bạn ơi!