Precalculus: Mathematics for Calculus, 7th Edition

The real part of the complex number $2-\sqrt -5$ is 2, and the imaginary part is $-\sqrt 5$.
Complex numbers are written in the form a+bi, with a being the real number and b being the imaginary number. Since, in this case, a=2, 2 is the real part of the complex number. b=$-\sqrt 5$, because $-\sqrt -5 = i*-\sqrt 5$ since $i=\sqrt -1$. Therefore the imaginary part (b) of the complex number = -5.