Subtract 8√23−√23

To subtract \( 8\sqrt{23} - \sqrt{23} \), you can combine the like terms:

\[
8\sqrt{23} - \sqrt{23} = (8 - 1)\sqrt{23} = 7\sqrt{23}
\]

So the answer is:

\[
7\sqrt{23}
\]

Therefore, the correct response is:

**7√23**