Chapter 1, Equations and Graphs - Section 1.5 - Complex Numbers - 1.5 Exercises - Page 131: 16

real part: 2 imaginary part: $-\sqrt{5}$

If the complex number is $a+bi$, then the real part is $a$ and the imaginary part is $b$. We have $2-\sqrt{-5}=2-\sqrt{5}i$, so the real part is $2$ and the imaginary part is $-\sqrt{5}$.