Respuesta :
sub
since -x^2+x+19=y
x=-x^2+x+19+80
x=-x^2+x+99
0=-x^2+99
x^2=99
x=3√11
x=y+80
3√11=y+80
minus 80 both sides
-80+3√11=y
x=3√11
y=-80+3√11
solution
(x,y)
(3√11,-80+3√11)
x=y+80
3√11=y+80
minus 80 both sides
-80+3√11=y
x=3√11
y=-80+3√11
solution
(x,y)
(3√11,-80+3√11)