Let's replace every copy of x with 7 and simplify.
Which is clearly false. This is probably the set of steps you followed to get "no solution".
Why is there no solution? Well let's subtract 9 from both sides to isolate the square root
Recall that the result of a square root operation is never negative. The range of and
is the set of nonnegative numbers. There is no way we can have the left hand side result in -6
If there was a negative sign out front the square root and we have this instead
then the answer would be x = 7
Unfortunately, there isn't such a negative sign, so we stick with "no solutions".