The discriminant tells us there are two roots when positive, one root when zero, and no roots when negative. b^2-4ac = (-8)^2-4*3*1 = 52 is positive, so there are two roots. The discriminant is just part of the quadratic equation. The quadratic equation gives us the exact real number roots of any equation in the form ax^2+bx+c=0. The quadratic equation is x = (-b \pm sqrt(b^2-4ac))/(2a), where \pm means that we have two values, one using + (addition) and one using - (subtraction). Let D = b^2-4ac.
A data warehouse is a special type of database used for analysis of data. A general database is usually used for transaction processing, and hence, it is not optimized for analysis and reporting. But a data warehouse is specially designed and optimized for analysis tasks.
Database programs create files of information. Compilers read source files and generate executable files. A file itself is a bunch of bytes stored on some storage device like tape, magnetic disk, Optical disk etc. The data files are the files that store data pertaining to a specific application, for later use.