By definition, either or . Alternatively, you could square both sides, to give and solve as a quadratic.
Also, by some geometric reasoning, you should know that means " is units away from ."
So in the case of your equation , by the definition of the modulus function, that means
So now you need to solve the equation for the two separate cases.
This solution is valid since it fits in with the restriction.
This solution is also valid since it fits with the restriction.
Now if you wanted to use the geometric interpretation...
So you are looking for the values of which are units away from .
Clearly these are and .