Question

5. Quantas raizes reais tem a equação x²+x-12=0?

a) Très raizes reais

b) Duas raizes reais

c) Uma raiz real

d) Nenhuma raiz real

Answer 1

Resposta:

$x^2+x-12\\\\\Delta=1^2-4.1.(-12)\\\Delta=1+48\hspace{2}\therefore\hspace{2}\Delta=49\\\\x=\frac{-1\pm\sqrt{49}}{2.1}=\frac{-1\pm7}{2}\\\\x_1=\frac{-1+7}{2}\therefore x_1=3\\\\x_2=\frac{-1-7}{2}\therefore x_2=-4$

LETRA (B), possui duas raízes reais distintas.