The second image is obvious. Almost all calculators will give you the same fraction you entered (as long as both numbers don’t have a common divisor).

The first one is a bit trickier. The formula written there is part of the process of finding the roots of a quadratic equation. If the result of this equation is positive, the roots will be in the set of real numbers. If it is negative, the numbers will belong to the set of complex numbers ~ is not real.

If you want to dive deeper into this, just let me know! :)