#### Answer

not a real number

#### Work Step by Step

As shown on page 445, we know that $a^{\frac{m}{n}}=\sqrt[n] a^{m}=(\sqrt[n] a)^{m}$.
Therefore, $(-144)^{\frac{1}{2}}=\sqrt[2] (-144)^{1}=\sqrt -144=$not a real number.
We know this because there is no real number $a$, such that $a^{2}=-144$.