A variable is a letter or symbol used as a placeholder for an unknown value.
Example: X apples
A constant can be a letter or a symbol that represents a fixed number.
Look at two examples of situations in which letters are substituted for numbers.
EXAMPLE 1
Suppose that a student is taking three technology-related classes.
- Each specific class can have one exam per week at most.
- Therefore, in any one-week period, the student may have 0, 1, 2, or 3 exams for the three classes.
- In algebra, the letter X can represent the number of exams the student may have in a one-week period.
- The letter X is a variable since it can represent any of the numbers: 0, 1, 2, 3.
EXAMPLE 2
Suppose you must report the total number of software programs used in the computer lab during the spring semester at your college.
- Since you do not know this number off the top of your head, you decide to represent it (at least temporarily) with the letter S.
- Later, you make a list of the available software programs and add up the total number. You find there are a total of seven computer software programs being used.
- The letter S, which represents this number then, is 7.
- Since S cannot represent any other values, the value S is constant.
HERE WE HAVE A LITTLE EXPLANATION ABOUT ALGEBRA
EXPRESSING PHRASES INTO EQUATIONS.
To solve real-world problems, you need to translate verbal phrases and sentences into variable expressions and equations. Look for key words that indicate the different operations.Note: Order is important in subtraction and division expressions. For example, “2 less than a number” is written as x- 2 , (not 2 - x ). The same way “a number divided by 5” is x / 5 (not 5 / x ).
That's everything for today hope you understood.
