Question

Por favor, alguém sabe esse sitema? E explica tb pff!

Answer 1

$\left \{ {{x^{2}-yx^{2}=8}\atop {x+y=4}} \right. =\left \{ {{x^{2}-y^{2}=8} \atop {x=4-y}} \right. (4-y)^2-y^2=8 y=1 x=4-1 x=3 (x,y)=(3,1) \left \{ {{3^2-1^2=8} \atop {3+1=4}} \right. \left \{ {{8=8} \atop {4=4}} \right. (x,y)=(3,1)$