If the range of $X$ is the set of all positive real numbers, show that for $k>0$ the probability that $\sqrt{2 X}-\sqrt{2 v}$ will take on a value less than $k$ equals the probability that $\frac{X-v}{\sqrt{2 v}}$ will take on a value less than $k+\frac{k^{2}}{2 \sqrt{2 v}}$