Question

Se x+2y=5 e 2x-2y=-14 então o valor de x+y é igual a

Answer 1

$\left \{ {{ x+2y=5} \atop {2x-2y=-14}} \right.$

$(2x-2y)+(x+2y)=-14+5$

$2x-2y+x+2y=-9$

$3x=-9$

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

$x=-3$

$x+2y=5$

$-3+2y=5$

$2y=5+3$

$2y=8$

$y=\frac{8}{2}$

$y=4$

$x+y=-3+4=1$