Question

resolva o sistema pelo método da adição:
{x+y=16
{x-y=4

Answer 1

x-y=4
x=4+y

4+y+y=16
2y=16-4
2y=12
y=12/2
y=6

x=4+6
x=10

Resposta:
x=10 y=6

Answer 2

$2x=20 x=\frac{20}{2} x=10 \left \{ {10+y=16} \atop {10-y=4}} \right. = \left \{ {y=16-10} \atop {-y=4-10}} \right. = \left \{ {{y=6} \atop {-y=-6}} \right.$