Mathematical symmetry is thought to be much too difficult for most laypeople to understand, but this engaging book approaches it in an elegantly entertaining way. The title's formula is the "quintic" equation (involving x raised to the fifth power), the analysis of which gave rise to "group theory," the mathematical apparatus scientists use to explore symmetry. A leading astrophysicist, Livio, keeps the science flowing with digressions into human interest (e.g., the founder of group theory, Evariste Galois, was a revolutionary firebrand who died in 1832 at age 20 in a duel over "an infamous coquette"), pop psychology (women have more orgasms when their partners have symmetrical faces), and strategies for finding a soul mate, as well as appreciations of art and music.