Question

Resolva a inequação x2 -x -2 <0
Preciso da parábola também

Answer 1

Boa noite!

Solução!

$x^{2} -x-2\ \textless \ 0$

$a=1\\\\\ b=-1\\\\\ c=-2$


$Formula!\\\\\\\\\\ x= \dfrac{-b\pm \sqrt{b^{2}-4.a.c } }{2.a}\\\\\\\\\\ x= \dfrac{-(-1)\pm \sqrt{(-1)^{2}-4.1.(-2) } }{2.1}\\\\\\\\\ x= \dfrac{1\pm \sqrt{1+8 } }{2}\\\\\\\\\ x= \dfrac{1\pm \sqrt{9 } }{2}\\\\\\\\\ x= \dfrac{1\pm 3}{2}\\\\\\\\\ Raizes!\\\\\\\\ x_{1}= \dfrac{1+3}{2}= \dfrac{4}{2}=2\\\\\\\ x_{2}= \dfrac{1-3}{2}= \dfrac{-2}{2}=-1$


$\boxed{Resposta:S=\{x \in\mathbb{R}|-1\ \textless \ x\ \textless \ 2\}}$


Da uma olhada no gráfico!

Boa noite!
Bons estudos!