1. a. 
contains

, and is radical over

because

has the required properties.
2. a. If
f =
x5 − 4
x − 2 then
f′ = 5
x4 − 4 is zero at ±
a, ±
ai where

. We find
f =
x(
x4 − 4) − 2 so

while

. As in Example 1, this shows that
f has three real roots and two (conjugate) nonreal roots. Since
f is irreducible by the Eisenstein criterion, its Galois group is
S5 as in Example 1.
3. Take
p =
x7 − 14
x + 2. Then
p′ = 7(
x6 − 2). If

then
p′ = 0 if
n = ±
a,
aw,
aw2,
aw4,
aw5 where

. Also
p =
x(
x6 − 14) + 2 so
and
Thus p has three distinct real roots and the rest complex (conjugate ...