Exercice 1.8 Galois Theory Ian Stewart

:نویسندهortollj

use the identity:cos(3(theta)=4(cos(theta))^3 - 3cos(theta) to solve the cubic equation t^3 + pt +q =0 with -27q^2 - 4p^3 >0 (3 real roots)

a discussion about that on math forum