What is an exact solution for
[tex]m \sqrt{14} [/tex]

Answer: Choice B) [tex]\sqrt{14}[/tex]
We have some value m and we're squaring it to get [tex]m^2[/tex]
To undo this and isolate m, we apply the square root to both sides
[tex]m^2 = 14\\\\\sqrt{m^2} = \sqrt{14}\\\\|m| = \sqrt{14}\\\\m = \sqrt{14} \text{ or } m = -\sqrt{14}[/tex]
There are two solutions here. This is similar to how there are two solutions in something like [tex]x^2 = 25[/tex] (those two solutions being x = 5 and x = -5). Squaring any negative number leads to a positive result because
negative times negative = positive.