Question

Resolva a inequação :
(-x-2)(2x+5)(x² + 3x +5) < 0

Answer 1

Observa que el discriminante del polinomio x² + 3x +5 es

$\Delta = 9-4(1)(5)= -11\ \textless \ 0$

Por esta razón 

$x^2 + 3x +5\ \textgreater \ 0\; , \;\forall x\in \mathbb R$

entonces

$(-x-2)(2x+5)(x^2+3x+5)\ \textless \ 0\iff (x+2)(2x+5)\ \textgreater \ 0\\ \\ \boxed{x\in(-\infty,-2)\cup (-5/2,+\infty)}$