Question

phân tích đa thức thành nhân tử

1)x³+6x²-13x-42

2)2x³-x²+3x+6

Answer 1

\(x^3+6x^2-13x-42\)

\(x^3+6x^2-13x-42\)

\(=\left(x+7\right)\left(x-3\right)\left(x+2\right)\)

Answer 2

b, \(2x^3-x^2+3x+6\)

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

\(=2x^2\left(x+1\right)-3x\left(x+1\right)+6\left(x+1\right)\)

\(=\left(x+1\right)\left(2x^2-3x+6\right)\)

Answer 3

\(x^3+6x^2-13x-42\)

\(=x^3+7x^2-x^2-7x-6x-42\)

\(=x^2\left(x+7\right)-x\left(x+7\right)-6\left(x+7\right)\)

\(=\left(x+7\right)\left(x^2-x-6\right)\)

\(=\left(x+7\right)\left(x-3\right)\left(x+2\right)\)