Question

Resolver os sistemas abaixo relacionados {x-3y =9 2x+3y = 6

Answer 1

$\left \{ {{x-3y=9} \atop {2x+3y=6}} \right.$

$x=9+3y$

$2x+3y=6$

$2(9+3y)+3y=6$

$18+6y+3y=6$

$9y=6-18$

$x=-\frac{12}{9} =-\frac{4}{3}$

$x=9+3y$

$x=9+3(-\frac{4}{3})$

$x=9+(-\frac{12}{3})$

$x=9+(-4)$

$x=9-4=5$

x=5 e y=$-\frac{4}{3}$