Question

phân tích thành nhân tử

x³ - 19x - 30

Answer 1

\(x^3-19x-30=\left(x-5\right)\left(x+2\right)\left(x+3\right)\)

Answer 2

\(x^3-19x-30\)

\(=x^3+2x^2-2x^2-4x-15x-30\)

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

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

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