You can
put this solution on YOUR website!to get the unit vector you need to get the magnitude of the vector and then divide each measure used by the magnitude.
-----
in your problem, you have (i,j,k) = (3,1,2)
magnitude =

=

=

=

.
-----
you take each measure and divide by the magnitude to get (

,

,

)
-----
you simplify the fraction by multiplying each by

to get (

,

,

) which can be simplified further to get (

,

,

) although I think I would want to keep all denominators the same.
-----
your answer will either be (

,

,

) or (

,

,

)
-----
this is a unit vector because the magnitude is now 1 as shown by the following equation:
magnitude of vector =

-----
this becomes

which becomes

which becomes

which becomes

.
-----
A unit vector in the opposite direction would have the same values only negatives of whatever is there.
In this case, your unit vector in the opposite direction should be (

,

,

)
-----
Note that keeping the denominator the same seemed like a good idea especially when verifying that the magnitude is 1.
-----