Question

Descompuneti în factori ireductibili,expresia x la a treia minus 3x la a doua minus 4x plus 12​

Answer 1

$x^3 -3x^2-4x+12=x^2(x-3)-4(x-3)=(x^2-4)(x-3)=(x-2)(x+2)(x-3)\\ \\ \\ \\ \boxed{a^2-b^2=(a-b)(a+b)}$

Answer 2

 

$\displaystyle\\~~~~x^3 - 3x^2 - 4x + 12=\\\\=\underbrace{x^3 - 3x^2} \underbrace{- 4x + 12}=\\\\=x^2(x - 3) - 4(x - 3)=\\\\=(x-3)(x^2-4)=\\\\=(x-3)(x^2-2^2)=\\\\=\boxed{\bf(x-3)(x-2)(x+2)}$