Na to nepotrebuješ skúšať kombinácie:

a) x+y = x-y, x*y = x/y
x+y = x-y => y = -y => y = 0
x*y = x/y => x*y^2 = x => y^2 = 1 => y = 1
=> nemá riešenie

b) x+y = x*y, x-y = x/y
x+y = x*y => x*y - y -x = 0
x-y = x/y => x*y - y^2 -x = 0
=> y^2 = y => y=1
x+1 = x
x-1 = x
=> nemá riešenie

c) x+y = x/y, x-y = x*y
x+y = x/y => x*y + y^2 -x = 0
x-y = x*y => x*y + y -x = 0
=> y^2 = y => y=1
x+1 = x
x-1 = x
=> nemá riešenie