# A problem with changing rings

Why is this piece of code not working?

```
a = 1; b = 1; c = 1; m = 1; k = 6; w = exp((2*pi*I*m )/k)
p = x^4 - 6*x^2 -x *(w^(a-c) + w^(c-a) + w^b + w^(-b) + w^(b-c) + w^(c-b) + w^a + w^(-a)) + (3 -w^c - w^(-c) - w^(a+b-c) - w^(-a-b+c) - w^(a-b) - w^(-a+b))
g = real_part(p).simplify()
q = g.change_ring(QQbar)
```

I would have thought that I can get the exact roots of `q`

above using `.solve`

since in the field of algebraic numbers (`QQbar`

) the above should have exact roots.

It has been answered in your previous question, where you could discover the difference between a symbolic expression and a genuine polynomial.