When you take the square root of a plus number, you get 2. It is often written as +/- something.
For example sqrt 64 = +8 and - 8
(8)*(8) = 64
(-8)(-8) = 64 Remember when 2 minus' are multiplied together, you get a plus.
Oddly, when you take the cube root of something, you get only 1 answer. When you take an advanced math course, you will find out that it is three. But until you know what a complex number is, the answer is 1.