Question

(X+3).(X-4).(X+2)

=

=

Answer 1

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

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

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

\(=\left(x^2-4x+3x-12\right)\left(x+2\right)\)

\(=\left(x^2-x-12\right)\left(x+2\right)\)

\(=x^2\left(x+2\right)-x\left(x+2\right)-12\left(x+2\right)\)

\(=x^3+2x^2-x^2-2x-12x-24\)

\(=x^3-x^2-12x-24\)

P/s: Ko chắc!

Answer 2

Sửa lại bước cuối: \(x^3+x^2-14x-24\)