Whether an answer is right or wrong is not a thing a moderator should look into. They are not here as judge on the correctness of answers. They have other serious issues to deal with. They just work for maintaining peace and order in the community.
Let the community decide (rather than an individual) the acceptability of an answer. The right way to deal with a wrong answer is to down vote. This is the power SE gives to its community. So use it wisely. Also IMHO you should comment before your down-vote so that the OP can understand what is wrong with the post and (hopefully) he can rectify it.
Using FLAG in these cases is likely to return you the result as @hims056 commented,
declined - flags should not be used to indicate technical inaccuracies, or an altogether wrong answer