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Math Symbols
The Most Valuable and
Important

Miscellaneous Symbols
. . .
Shown and Explained

"Plus-Minus Sign"



Math - Plus-Minus

Plus-Minus Sign . . .


Background - why symbols are used . . .

Symbols are used as a concise way of giving lengthy instructions


related to numbers and logic.

Math Symbols are a communication tool. Symbols are an invention which is used to eliminate the need to write long, plain language instructions to describe calculations and other processes.

The most valuable, most frequently used Symbols in
mathematics . . .
:

The most important, most frequently used Miscellaneous symbols are listed below.

Math - Plus-Minus Math Symbol for "Plus-Minus" -


The Math - Plus-Minus symbol symbol means that the number (to the right of the symbol) is really two numbers: a positive number AND a negative number.


For Example, Math - Plus-Minus symbol 8 stands for two numbers:


+8 and -8


The Math - Plus-Minus symbol symbol is commonly used:

(1) In mathematical expressions and equations.

(2) To quantify the margin or error (precision) of a computation or measurement.


Example 1: Math - Plus-Minus symbol , use in Mathematical Expressions and Equations


Square Root:

Square Root


The use of the plus-minus symbol is a short hand way of showing that the square root of 256 has two answers:

Square Root


Absolute Value:

Absolute Value


This absolute value equation can be rewritten using the plus-minus symbol:


Absolute Value


The use of the plus-minus symbol clearly shows that two equations must be solved to determine the values of x which satisfy the original equation. These equations are:

Absolute Value


Quadratic Equation:

Quadratic Equation


The use of the plus-minus symbol shows that two equations must be solved to determine which values of x satisfy the quadratic equation. These equations are:


(1) Using the "plus" sign:

Quadratic Equation


(2) Using the "minus" sign:

Quadratic Equation


Example 2: Math - Plus-Minus symbol , use in "Precision" or "Margin or Error"


Margin of Error:

A local poll taken May 1-4 of 1200 registered voters showed Candidate A would beat Candidate B if the election were held now, 60 to 30 percent, with seven percent undecided. This poll has a margin of error of plus or minus four percentage points.

Candidate A should receive between 56% and 64% of the vote if the election were held today.

This could be written:


Candidate A
Likely Vote Margin of Error


Engineering Tolerance:

A round pin is being manufactured to fit into a round hole, which is 20 mm in diameter. The round pin might have a manufacturing specification of 19.95 mm to 19.99 mm in diameter.

Using the plus-minus sign, this could be written:


Diameter of
Round Pin Engineering Tolerance

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