For x2−y2=15x^2 - y^2 = 15x2−y2=15, which pair (x,y)(x, y)(x,y) is a solution?
(4,1)(4, 1)(4,1)
(8,7)(8, 7)(8,7)
(4,−1)(4, -1)(4,−1)
(3,5)(3, 5)(3,5)