Question

phân tích đa thức thành nhân tử :

a) x^3+x^2+4

Answer 1

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

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

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

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

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

Answer 2

x³-2x-4 
=x³-4x+2x-4 
=x(x²-4)+2(x-2) 
=x(x-2)(x+2)+2(x-2) 
=(x^2+2x+2)(x-2) 

Answer 3

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

\(=x^3+\left[\left(x^2+2.2x+2^2\right)-4x\right]\)

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

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

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

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

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

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

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