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The same convention is also used in some computer languages. For example, subtracting −5 from 3 might be read as "positive three take away negative 5", and be shown as 3 − − 5 becomes 3 + 5 = 8, which can be read as: + 3 −1(− 5) or even as + 3 − − 5 becomes + 3 + + 5 = + 8.
In mathematical formulas, the ± symbol may be used to indicate a symbol that may be replaced by either of the plus and minus signs, + or −, allowing the formula to represent two values or two equations. [2] If x 2 = 9, one may give the solution as x = ±3. This indicates that the equation has two solutions: x = +3 and x = −3.
The plus and minus symbols are used to show the sign of a number. In mathematics, the sign of a real number is its property of being either positive, negative, or 0.Depending on local conventions, zero may be considered as having its own unique sign, having no sign, or having both positive and negative sign.
Since 2 × (−3) = −6, the product (−2) × (−3) must equal 6. These rules lead to another (equivalent) rule—the sign of any product a × b depends on the sign of a as follows: if a is positive, then the sign of a × b is the same as the sign of b, and; if a is negative, then the sign of a × b is the opposite of the sign of b.
In number theory, a perfect number is a positive integer that is equal to the sum of its positive proper divisors, that is, divisors excluding the number itself. For instance, 6 has proper divisors 1, 2 and 3, and 1 + 2 + 3 = 6, so 6 is a perfect number. The next perfect number is 28, since 1 + 2 + 4 + 7 + 14 = 28.
For example, the integers are made by adding 0 and negative numbers. The rational numbers add fractions, and the real numbers add infinite decimals. Complex numbers add the square root of −1. This chain of extensions canonically embeds the natural numbers in the other number systems. [6] [7] Natural numbers are studied in different areas of math.
The false positive rate (FPR) is the proportion of all negatives that still yield positive test outcomes, i.e., the conditional probability of a positive test result given an event that was not present. The false positive rate is equal to the significance level. The specificity of the test is equal to 1 minus the false positive rate.
In elementary mathematics, the additive inverse is often referred to as the opposite number, [3] [4] or its negative. [5] The unary operation of arithmetic negation [6] is closely related to subtraction [7] and is important in solving algebraic equations. [8] Not all sets where addition is defined have an additive inverse, such as the natural ...