Finding a $\gamma$ to define a number field like $E=\mathbb{Q}(\zeta_5)(X^5-\gamma)$
By working with eliptic curves, I found that the extension E defined by:
E.< a>
E.<a>
= NumberField(x^20 -
2x^19 2*x^19 - 2*x^18 + 18*x^17 - 32*x^16 + 88*x^15 + 58*x^14 -
2x^18 + 18x^17 - 32x^16 + 88x^15 +
58x^14 - 782x^13 + 1538x^12 +
1348x^11 - 466x^10 - 894x^9 +
346x^8 - 114x^7 - 424x^6 - 88x^5 +
214x^4 782*x^13 +
54x^3 1538*x^12 +
14x^2 1348*x^11 - 466*x^10 - 894*x^9 + 346*x^8 -
114*x^7 - 424*x^6 - 88*x^5 + 214*x^4 + 54*x^3 + 14*x^2 + 4*x +
1) 1)
Is a cyclic Kummer extension of degree $5$ over $\mathbb{Q}(\zeta_5)$, thus by the clasification of Kummer extensions, it there exists $\gamma \in \mathbb{Q}(\zeta_5)$ such that $E=\mathbb{Q}(\sqrt[5]{\gamma})$.
So, about all the polynomials $f$ that define $E$ how do I find $\gamma$ such that the polynomial $X^5-\gamma$ also define defines $E$?