Answer:
![[HI]_{eq}=0.942M](https://tex.z-dn.net/?f=%5BHI%5D_%7Beq%7D%3D0.942M)
Explanation:
Hello,
In this case, the initial concentrations of hydrogen and iodine are the same:
![[H_2]_0=[I_2]_0=0.600M](https://tex.z-dn.net/?f=%5BH_2%5D_0%3D%5BI_2%5D_0%3D0.600M)
Thus, considering the given undergoing chemical reaction, one states the law of mass action in terms of the change
due to the chemical change as shown below:

Therefore, solving for
by quadratic equation one obtains:

Nevertheless, the feasible result is the first one as the second one results in negative concentrations, thus, the hydroiodic acid equilibrium concentration turns out:
![[HI]_{eq}=2*0.471M=0.942M](https://tex.z-dn.net/?f=%5BHI%5D_%7Beq%7D%3D2%2A0.471M%3D0.942M)
Best regards.