The negative square root of 9 is -3. In mathematics, a rational number is defined as any number that can be expressed as the quotient or fraction p/q of two integers, where q is not zero. Since -3 can be written as -3/1, it meets the criteria for being a rational number.
To elaborate, the square root of a number represents a value that, when multiplied by itself, gives the original number. The negative square root refers to the negative value of that result. In this case, since 3 × 3 = 9, the negative square root is -3.
Therefore, yes, the negative square root of 9 is a rational number.