Is the square root of -4 irrational?

The square root of -4 is not irrational, it is imaginary. Irrational Numbers are numbers that cannot be expressed as a fraction, like the square root of 2. Irrational numbers, however, are a subset of real numbers. The square root of -4 however, is not even a real number because no real number, when squared, gives -4. Therefore the square root of -4 is an imaginary number.

In calculus, the root is expressed as 2i where iis the square root of -1.