If, for instance, the formula gives you (-6 ± √37) / 5
either leave it like that
or find a decimal approximation: (-6 ± 6.083) / 5 which reduces to 0.0166 and -2.4166.
If the radical can be reduced, such as √48, reduce it: 4√3, so (3 ± √48) / 6 becomes (3 ± 4√3) / 6
Then, if you want to make it into a decimal, you can.
In all cases, follow the instructions of your teacher.