Question

If `[x, y][(x),(y)] = [25]` and `[(-x, y)][(2x),(y)] = [-2]` find x and y if `x, y  ε  Z` (integer)

Answer 1

`[x,y][(x),(y)] = [25]`

`x^2 + y^2 = 25`

and 

`-2x^2 + y^2 = -2`

`x , y  ε  Z` (interger)

If can observed that that above two equation are satisfied when `x = +-3` and y = +-4