Solve $x^7-5x^4-x^3+4x+1=0$ for $x$ 
Solve for $x$
  $$x^7-5x^4-x^3+4x+1=0$$  

This equation has been bugging me since the past few days. I have found, using the Rational Root Theorem that $x=1$ is a root of this equation. However, after dividing, I cannot solve the six degree equation thus generated. I have also tried factorizing the equation, but it's not working.

$x^4(x^3 + 1) + (x^3 + 1) = 0$
$\implies(x^3 + 1)(x^4 + 1) = 0$
$\implies(x + 1)(x^2 - x + 1)(x^4 + 2x^2 + 1 - 2x^2) = 0$
$\implies(x + 1)(x^2 - x + 1)((x^2 + 1)^2 - 2x^2) = 0$
$\implies(x + 1)(x^2 - x + 1)(x^2 + 1 + (\sqrt 2)(x))(x^2 + 1 - (\sqrt 2)(x)) = 0$
$ x^2 - x + 1 = 0$
$\implies x = \frac{1 \pm \sqrt{1 - 4\times1}}2 = \frac{1 \pm i \sqrt 3}2$
$ x^2 + \sqrt 2x + 1 = 0$
$\implies x = \frac{-\sqrt 2 \pm \sqrt{2 - 4 \times 1}}2 = \frac{-\sqrt 2 \pm i \sqrt 2}2$
$ x^2 - \sqrt 2x + 1 = 0$
$\implies 4x = \frac{\sqrt 2 \pm \sqrt{2 - 4 \times 1}}2 = \frac{\sqrt 2 \pm i sqrt 2}2$
The $7$ roots of $x$ are:
$x = -1, \frac{1 \pm i \sqrt 3}2, \frac{-\sqrt 2 \pm i \sqrt 2}2, \frac{\sqrt 2 \pm i \sqrt 2}2$
