I want to solve
$$x^7+x^3+x-1=0.$$
I tried all possible factorization ways (over rational coefficients), e.g.
$$x^7+x^3+x-1=(x^3+ax^2+bx+c)(x^4+rx^3+sx^2+tx+u)$$
But, all possible cases didn't work. Could this equation be related to Galois Theory? Because the equation could not be factored.
Its Galois group is $S_7$, you can compute it in magma
It implies that must be irreducible, so you cannot factorice it in rationals.