(追記) (追記ここまで)
Square Root
A nonnegative number that must be multiplied times itself to equal a given number. The square root of x is written or x½. For example, since 32 = 9.
Note: never refers to a negative number. Even though (–3)(–3) = 9, we do not say that –3 is a value of . Also, if x itself is negative then is imaginary.
See also
nth root, cube root, square root rules, radical rules, rational exponents