Question

phân tích đa thức thành nhân tử:

\(x^3+6x^2-x-30\)

Answer 1

\(=\left(x^3-2x^2\right)+\left(8x^2-16x\right)+\left(15x-30\right)\)

\(=x^2\left(x-2\right)+8x\left(x-2\right)+15\left(x-2\right)\)

\(=\left(x-2\right)\left(x^2+8x+15\right)\)

\(=\left(x-2\right)\left(x^2+3x+5x+15\right)\)

\(=\left(x-2\right)\left[x\left(x+3\right)+5\left(x+3\right)\right]\)

\(=\left(x-2\right)\left(x+3\right)\left(x+5\right)\)