Answer
The expression is not a real number.
Work Step by Step
RECALL:
When the index, $n$ is even, the value of $a$ in $\sqrt[n]{a}$ cannot be negative since its nth root will not be a real number.
The given radical has an even index (8).
Since the number inside the radical is negative, its 8th root will not be a real number.
Thus, the given expression is not a real number.