x=9-y
(9-y)^2-y^2=72
81-18y=72
18y=9
y=0,5
x=8,5
x^2-y^2=72 x=9-y
(81-18y+y^2)-y^2=72
81-18y+y^2-y^2=72
-18y+81-72=0
-18y+9=0
y=18/9=0.5 x=8.5
x=9-y
(9-y)^2-y^2=72
81-18y=72
18y=9
y=0,5
x=8,5
x^2-y^2=72 x=9-y
(9-y)^2-y^2=72
(81-18y+y^2)-y^2=72
81-18y+y^2-y^2=72
-18y+81-72=0
-18y+9=0
18y=9
y=18/9=0.5 x=8.5