Someone recently asked me why a negative $\\times$ a negative is positive, and why a negative $\\times$ a positive is negative, etc. I went ahead and gave them a proof by contradiction like …

Mar 13, 2011 · A reasonable place to start is to search "strictly positive" or "strictly negative" in your favorite academic search engine. Those terms are used when there must be no …

The word that you are looking for is the very word that you are using and that word is sign. If you are looking for something more "academic", then you can use its Latin variant, signum. …

Oct 31, 2014 · The product of a positive number and a negative number is negative, except when the positive number happens to be zero, in which case the result is zero, hence positive The …

Apr 21, 2011 · The word is sign: In mathematics, the word sign refers to the property of being positive or negative. Every nonzero real number is either positive or negative, and therefore …

Oct 27, 2015 · For convenience, the square root of non-negative real numbers is usually taken to be the non-negative real value, but there is nothing other than practicality to stop you from …

Aug 11, 2014 · Because of the way negative number multiplication is defined (and it is a made up, abstract definition, it doesn't "come" from anywhere), it is the case that multiplying a negative …

Non-negative (real) numbers: $\mathbb {R}^+\cup\ {0\} = [0,\infty)$ That is to say, the difference between positive and non-negative numbers is that for positive numbers it does not include …

May 10, 2014 · 1 'Positive' and 'Negative' are defined only on the real number line, which is part of the system of complex numbers. So it makes sense to say, for example 1−100i 1 100 i is …

Jul 17, 2014 · I have a question about line integrals of vector fields being positive, negative, or zero. If you are measuring the work it takes to "push" a point on the curve through the vector …