To find the imaginary part of the complex number \( 9.2 - 3 - \sqrt{-8} \), we first need to simplify \( \sqrt{-8} \).
Recall that \( \sqrt{-8} \) can be expressed as:
\[ \sqrt{-8} = \sqrt{8} \times \sqrt{-1} = \sqrt{8} i \]
Since \( \sqrt{8} = \sqrt{4 \times 2} = 2\sqrt{2} \), we have:
\[ \sqrt{-8} = 2\sqrt{2} i \]
Now, substitute this back into the expression:
\[ 9.2 - 3 - \sqrt{-8} = 9.2 - 3 - 2\sqrt{2} i \]
Now simplify the real part:
\[ 9.2 - 3 = 6.2 \]
Thus, we can rewrite the complex number as:
\[ 6.2 - 2\sqrt{2} i \]
Here, the imaginary part is:
\[ -2\sqrt{2} \]
Therefore, the imaginary part of the complex number \( 9.2 - 3 - \sqrt{-8} \) is \(-2\sqrt{2}\).