isi-entrance 2016 Q61

isi-entrance · India · UGB 4 marks Number Theory Quadratic Diophantine Equations and Perfect Squares
If $n$ is a positive integer such that $8 n + 1$ is a perfect square, then
(A) $n$ must be odd
(B) $n$ cannot be a perfect square
(C) $2 n$ cannot be a perfect square
(D) none of the above
If $n$ is a positive integer such that $8 n + 1$ is a perfect square, then\\
(A) $n$ must be odd\\
(B) $n$ cannot be a perfect square\\
(C) $2 n$ cannot be a perfect square\\
(D) none of the above