Exchanging "+" and "" in the expression, i.e. permuting the two solutions of the equation can be viewed as a (very simple) group operation. Similar formulae are known for cubic and quartic equations, but do not exist in general for degree 5 and higher. Abstract properties of Galois groups associated with polynomials (in particular their solvability) give a criterion for polynomials that have all their solutions expressible by radicals, i.e. solutions expressible using solely addition, multiplication, and roots similar to the formula above.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What concept is associated with the solvability of polynomials?
Ah, so.. Abstract properties of Galois groups

During the ceremony of initiation, the candidate is expected to swear (usually on a volume of sacred text appropriate to his personal religious faith) to fulfil certain obligations as a Mason. In the course of three degrees, new masons will promise to keep the secrets of their degree from lower degrees and outsiders, and to support a fellow Mason in distress (as far as practicality and the law permit). There is instruction as to the duties of a Freemason, but on the whole, Freemasons are left to explore the craft in the manner they find most satisfying. Some will further explore the ritual and symbolism of the craft, others will focus their involvement on the social side of the Lodge, while still others will concentrate on the charitable functions of the lodge.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What are Freemasons required to do for their craft?
Ah, so.. unanswerable

Composers of classical music have often made use of folk music (music created by musicians who are commonly not classically trained, often from a purely oral tradition). Some composers, like Dvorak and Smetana, have used folk themes to impart a nationalist flavor to their work, while others like Bartok have used specific themes lifted whole from their folk-music origins.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): Folk musicians are not commonly what?
Ah, so..
classically trained