Chemistry: The Molecular Science (5th Edition)

We see that the upper reaction is the flipped version of the lower reaction, meaning that $K_{c1}$ is the inverse of $K_{c2}$. In addition, we see that the coefficients of the upper reaction are equal to exactly half of the coefficients of the lower reaction, meaning: $K_{c2}=\frac{1}{k_{c1}^2}$
We see that the upper reaction is the flipped version of the lower reaction, meaning that $K_{c1}$ is the inverse of $K_{c2}$. In addition, we see that the coefficients of the upper reaction are equal to exactly half of the coefficients of the lower reaction, meaning: $K_{c2}=\frac{1}{k_{c1}^2}$