Question

Phân tích đa thức thành nhân tử : a) x mũ 3 - 2.x -4

b) x mũ 3 - x mũ 2-4

c) 2.x mũ 3 - 5.x mũ 2 + 8.x-3

Answer 1

a: \(x^3-2x-4\)

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

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

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

b: \(x^3-x^2-4\)

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

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

c: \(2x^3-5x^2+8x-3\)

\(=2x^3-x^2-4x^2+2x+6x-3\)

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