kill(all);

load(ntrig)$

van=facebook.com/LearningCalculus$

y(x):=x^5-1;

S:solve(y(x),x)$

X:create_list(rhs(S[i]),i,1,5);

N:(1-X[1])*(1-X[2])*(1-X[3])*(1-X[4]);

trigsimp(realpart(N));