Why does calculator say that $\sqrt{4} = 2$?

Question

Possible Duplicate:
Square roots — positive and negative

I know that the square roots of four are

2 because $2^2=4$
and $-2$ because $(-2)^2=4$

Are there any conventions in considering primarily the positive square root or adding the $\pm$ symbol in the calculator screen would be a cost factor?

There might be even better duplicates, but this one seems adequate. — Asaf Karagila, Oct 01 '12 at 11:20
By definition the symbol $\sqrt{x}$ denotes the non-negative square root of $x$. — Brian M. Scott, Oct 01 '12 at 11:30

score 1 · Answer 1 · answered Oct 01 '12 at 11:22

1

The very same question could also apply to other functions (e.g. trigonometric functions). SQRT is defined as returning only the +ve value of the square root. Check here for a thorough discussion on this topic: http://forums.randi.org/archive/index.php/t-36241.html.

answered Oct 01 '12 at 11:22

Epictetus

141

If by "thorough" you mean "long and full of misconseptions", then by all means it's thorough. – mrf Oct 01 '12 at 13:03

Why does calculator say that $\sqrt{4} = 2$?

1 Answers1