Respostas

2014-05-28T12:29:16-03:00
 \left \{ {{xy-6=0} \atop {2x+3y=12}} \right.

 \left \{ {{xy=6} \atop {2x+3y=12}} \right.

y= \frac{6}{x}

2x+3.\frac{6}{x} =12

x+3.\frac{3}{x} =6

x+\frac{9}{x} =6

 x^{2} +9 =6x

 x^{2}- 6x+9 =0

(x-3)^{2} =0

x-3 =0

x=3 ⇒ duas raízes reais e iguais

y= \frac{6}{x}= \frac{6}{3}=2