Answer:
In Real numbers: none (defined for all real numbers)
In Complex numbers: not defined for x = 2i, -2i
Explanation:
Fraction becomes undefined when the denominator = 0
x² + 4 = 0
Has no real solutions
The fraction is defined for all real values of x
x² + 4 = 0
x² = -4
x = 2i, -2i
The fraction is not defined for x = +/-2i (in Complex Numbers)