Question

Phân tích đa thành nhân tử:

a)x(x³-4)+2x³-4

b) (1+2x)(1-2x)-x(x+2)(x-2)

Answer 1

a: \(x\left(x^3-4\right)+2x^3-4\)

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

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

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

b: \(\left(1+2x\right)\left(1-2x\right)-x\left(x+2\right)\left(x-2\right)\)

\(=1-4x^2-x\left(x^2-4\right)\)

\(=1-4x^2-x^3+4x\)

\(=-\left(x^3-1+4x^2-4x\right)\)

\(=-\left[\left(x-1\right)\left(x^2+x+1\right)+4x\left(x-1\right)\right]\)

\(=-\left(x-1\right)\left(x^2+5x+1\right)\)