Question

Phân tích đa thự thành nhân tử

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

Answer 1

x³ - 6x² - x + 30

= (x + 2).x² - 6x² - x + 30/x + 2

= x² - 8x + 15

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

Answer 2

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

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

\(=x\left(x^2-8x+15\right)+2\left(x^2-9x+15\right)\)

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

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

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

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