х^2+y^2=2.5xy
x-y=0.25xy
(x-y)(x+y)=2.5xy
x-y=0.25xy
тогда я получаю
0.25xy(x+y)=2.5xy
x+y=2.5xy/0.25xy
x+y=10
x=10-y
(10-y)^2+y^2=2.5y(10-y)
100-20y-y^2=25y-2.5y^2
4.5y^2-45y+100=0 /5
0.9y^2-9y+20=0
D=81-72=9
y1=12/1.8=6(2/3) x1=10-6(2/3)=3(1/3)
y2=3(1/3) x2=10-3(1/3)= 6(2/3)
ответ: х1=3(1/3) у1= 6(2/3)
х2= 6(2/3) у2= 3(1/3)