The word exact here is an inexact description of what sort of solution this really is - it's a closed form explicit solution. A closed form solution means that

The word exact here is an inexact description of what sort of solution this really is - it's a closed form explicit solution. A closed form solution means that the equation is limited to to certain common mathematical operations and is finite in length. An explicit solution means that the quantity we are solving for is isolated on one side of the equation.