In a recent quiz we where asked the square root of four. The quizmaster gave the answer as not only 2 but also -2. Being pedantic I queried this. Although -2 squared is 4, does it follow that the root of 4 is -2 Can you enlighten us?
It depends whether you define "square root of 4" as "the positive number
whose square is 4" or "any number whose square is 4". I think that in
the question "Find the square root of 4", the first definition is
implicit, otherwise you should have been asked "Find all square roots
If the instructions were
then the answer is 2. The surd symbol, applied to a non-negative real number x, always returns the non-negative real number y that satisfies y 2 = x.
Claude and Penny