Which of the following is true for x2−y2=kx^2 - y^2 = kx2−y2=k?
Unsolvable if k≡2(mod4)k \equiv 2 \pmod 4k≡2(mod4)
Always solvable for odd kkk
Solvable if 4∣k4 | k4∣k
All of the above