Question

Question was provided via image upload.

Explanation:

Step1: Rewrite -144 as product

$\sqrt{-144} = \sqrt{-1 \cdot 12^2}$

Step2: Separate imaginary unit

$\sqrt{-1 \cdot 12^2} = i \cdot \sqrt{12^2}$

Step3: Simplify the radical

$i \cdot \sqrt{12^2} = 12i$

Answer:

Blanks (in order): -1, $i$, $12i$