“Ordering Roots”: Does the approach of simply squaring each value hold every time?

Question

Does the approach of simply squaring each value hold every time? In other words, 2 times root of 13 squared etc. This way I got values 52, 48, 50 and 54 which helped me to line them up correctly.

Answer

Yes, this works, because all the numbers are positive. Obviously, if one or more of the numbers were negative, squaring them would result in positive numbers, which could change the order. But, yes, as it is, with positive numbers, this will always hold.

One other thing - make sure you square both the value inside and outside the root. 

Link

http://gmat.magoosh.com/questions/726