Evaluate square root of 24 - x when x = 6 . write the answer in simplified radical form.?

So, first we input 6
24 - 6 = 18
So we now need to find the square root of 18
If you're allowed to use a calculator, the square root is 4.242

But if you don't, let's get as close as we can:
√(9 * 2)
Because the square root of 9 is 3:
3 * √2