#### Answer

All numbers, except $\sqrt{-4}$.

#### Work Step by Step

All of the numbers are real, except $\sqrt{-4}$. This number is not real because square roots are only defined for positive numbers (i.e. $\sqrt{x}, x\geq0$).

Published by
Pearson

ISBN 10:
0321969359

ISBN 13:
978-0-32196-935-4

All numbers, except $\sqrt{-4}$.

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