Question

Arătați că sunt egale : $x(x-2)^{2} +2(3x^{2} -1)-5x=(x-1)(x+1)(x+2)$

Answer 1

$\rm x(x-2)^{2} +2(3x^{2} -1)-5x=(x-1)(x+1)(x+2) \\ \\ x(x^2-4x+4)+6x^2-2-5x=(x^2-1)(x+2) \\ \\ \not x^3-4x^2+4x+6x^2-\not2-5x=\not x^3+2x^2-x-\not2 \\ \\ 6x^2-4x^2+4x-5x= \bold{2x^2-x~(adev\v arat)}$