kill(all);

van=facebook.com/LearningCalculus$

P(x):=8*x^3-4*x+1$

x:solve(P(x),x);

M:matrix ([rhs(x[1]), 0, 0], [0, rhs(x[2]), 0], [0, 0, rhs(x[3])]);

M.M;

determinant(M.M);

radcan(%);