It would be 5 and anything above 5
And it would be - 5 and anything below - 5
Because 4^2 is 16 and anything below 4 is smaller than 18.
So it would be 5 because if you square any number above 4 its bigger than 18.
Also it would be anything below - 5 because as an example:
-5*-5 = 25
-6*-6 = 36
As u can see when you square any negative numbers below - 5 (including - 5) it fits into the inequality
