Х + 4у = 10
Х = 10 - 4у
Х^2 = 100 - 80у + 16у^2
Х^2 + ху = - 2
100 - 80у + 16у^2 + у( 10 - 4у ) = - 2
100 - 80у + 16у^2 + 10у - 4у^2 + 2 = 0
12у^2 - 70у + 102 = 0
6у^2 - 35у + 51 = 0
D = 1225 - 1224 = 1
y1 = ( 35 + 1 ) : 12 = 3
y2 = ( 35 - 1 ) : 12 = 17/6 = 2 5/6
X1 = 10 - 4•3 = - 2
X2 = 10 - 4•( 17/6 ) = 10 - ( 34/3 ) = 10 - 11 1/3 = - 1 1/3
Ответ ( - 2 ; 3 ) ; ( - 1 1/3 ; 2 5/6 )