Система:

ху+х=56

ху+у=54

X (y+1) = 56

xy+y=54

x=56 / (y+1)

56y / (y+1) + y = 54

56y + y² + y = 54y + 54

y² + 3y - 54 = 0

D=9+216 = 225

y₁ = (-3+15) / 2=6

y₂ = (-3-15) / 2 = - 9

x₁ = 56 / (6+1) = 8

x₂ = 56 / (-9+1) = - 7

Ответ; (8; 6); (-7; -9)