The function is
.
Apply derivative on each side with respect to
.

The derivative function is always positive, since
and
is any positive integer.
The only way a function
have a positive derivative for
is function to be monotonically increasing.
A monotonically increasing function can cross the
axis at most once.
Therefore
has a atleast one real root.
The other roots must be complex.
\Therefore the polynomial function
cannot have two real roots.
The polynomial function
cannot have two real roots.