Question

Ajudem?

1. Calcule o valor de 2x-y no sistema: {3x +{y=1} 
                                                             {x+3y=-5}

Answer 1

$\left \{ {{3x+y=1(-3)} \atop {x+3y=-5}} \right. \\ \\ \left \{ {{-9x-3y=-3} \atop {x+3y=-5}} \right. \\ \\ -8x=-8(-1) \\ 8x=8 \\ \\ x=1 \\ \\ 3x+y=1 \\ 3*(1)+y=1 \\ 3+y=1 \\ \\ y=-2 \\ \\ ------------------------------ \\ \\ 2x-y=2*(1)-(-2)=4$