To combine the radicals \( 9\sqrt{24} - 5\sqrt{6} + 3\sqrt{54} \), we'll first simplify each radical:
-
Simplifying \( \sqrt{24} \):
\[
\sqrt{24} = \sqrt{4 \cdot 6} = \sqrt{4} \cdot \sqrt{6} = 2\sqrt{6}
\]
So,
\[
9\sqrt{24} = 9 \cdot 2\sqrt{6} = 18\sqrt{6}.
\]
-
Simplifying \( \sqrt{54} \):
\[
\sqrt{54} = \sqrt{9 \cdot 6} = \sqrt{9} \cdot \sqrt{6} = 3\sqrt{6}
\]
So,
\[
3\sqrt{54} = 3 \cdot 3\sqrt{6} = 9\sqrt{6}.
\]
Now, we can substitute these simplified forms back into the original expression:
\[
9\sqrt{24} - 5\sqrt{6} + 3\sqrt{54} = 18\sqrt{6} - 5\sqrt{6} + 9\sqrt{6}.
\]
Now, combine the terms involving \(\sqrt{6}\):
\[
(18 - 5 + 9)\sqrt{6} = (18 + 9 - 5)\sqrt{6} = 22\sqrt{6}.
\]
So, the final result is:
\[
22\sqrt{6}.
\]
Thus, the correct answer is:
\[
22\sqrt{6}.
\]