Simple integral question for expression of constant term

Question

$\frac{dy}{dx}\ = \frac{-1}{x^3}\\$

is the solution:

$y = \frac{1}{2x^2} + k$

or

$y = \frac{1}{2x^2} - k$

Answer 1

Both are correct, with the understanding that $k$ is an arbitrary constant.