a/ Bạn coi lại đề
b/ \(x^3-4x^2-4x-5\)
\(=x^3+x^2+x-5x^2-5x-5\)
\(=x\left(x^2+x+1\right)-5\left(x^2+x+1\right)\)
\(=\left(x-5\right)\left(x^2+x+1\right)\)
c/ \(x^3-2x^2+5x+8\)
\(=x^3-3x^2+8x+x^2-3x+8\)
\(=x\left(x^2-3x+8\right)+\left(x^2-3x+8\right)\)
\(=\left(x+1\right)\left(x^2-3x+8\right)\)
d/
\(3x^3-7x^2+17x-5\)
\(=3x^3-6x^2+15x-x^2+2x-5\)
\(=3x\left(x^2-2x+5\right)-\left(x^2-2x+5\right)\)
\(=\left(3x-1\right)\left(x^2-2x+5\right)\)
e/
\(4x^3-13x^2+9x-18\)
\(=4x^3-x^2+6x-12x^2+3x-18\)
\(=x\left(4x^2-x+6\right)-3\left(4x^2-x+6\right)\)
\(=\left(x-3\right)\left(4x^2-x+6\right)\)