isi-entrance 2021 Q20

isi-entrance · India · UGA Number Theory Quadratic Diophantine Equations and Perfect Squares

The number of all integer solutions of the equation $x ^ { 2 } + y ^ { 2 } + x - y = 2021$ is
(A) 5 .
(B) 7 .
(C) 1 .
(D) 0 .

The number of all integer solutions of the equation $x ^ { 2 } + y ^ { 2 } + x - y = 2021$ is\\
(A) 5 .\\
(B) 7 .\\
(C) 1 .\\
(D) 0 .