If you use your calculator, you can notice that and that . In fact, and generally speaking : . This property is not working with additions, you can check with your calculator that : and that . Both do not give the same result.
Therefore, you can reduce the number with its square root. You agree that (3 things plus 5 things, it makes 8 things). So, you are able to solve the following great problem : writing with only one square root the numbers E and F.