Any numbers can be used in a square root. The square root symbol (#sqrt#) is called a radical and the number whose square root is being considered is called a radicand. All nonnegative real numbers have two possible square roots: a positive and a negative one. For example, #sqrt(5)# can be equal to #5# of #-5# as the product of two negative numbers is always positive. When a negative number is the radicand, the answer will be in terms of #i#, which is an imaginary number that is #sqrt(-1)#. For example, #sqrt(-5) = sqrt(-1)*sqrt(5) = isqrt(5)#.