Home |
## Variables and Expressions
The most important concept in algebra is that of a variable. This is a concept that you may have seen before, but it is important to begin by reviewing and discussing this concept. Remember that a variable is simply a letter or sometimes a symbol used to represent a quantity. For example, suppose b represents the number of boys in the class and g represents the number of girls. A verbal expression like "There are 14 girls in the class." can be written as an algebraic expression or equation, which involves a variable. g = 14 We can also write a verbal expression from an algebraic one. Because we know that the variable b represents the number of boys in the class, the algebraic equation b = 15 can be translated to the verbal sentence "There are 15 boys in the class." ## What is an algebraic expression?Have a look at these definitions: - A
**variable**is a letter or symbol used to represent a quantity.
- An
**algebraic expression**consists of one or more numbers and variables along with one or more arithmetic operations.
Some examples of algebraic expressions are shown below. You might write a table like the following to show the relation between verbal and algebraic expressions.
Remember the terms that describe expressions like x Translating between algebraic and verbal expressions.
Write an algebraic expression for the sum of 3 and the number x divided by 16.
Write an algebraic expression for six subtracted from the number y, all raised to the fourth power.
Write a verbal expression for 5m - n
The product of 5 and the number m minus the number n raised to the second power (or n squared)
Write a verbal expression for ( x + 2)
The sum of the number x and 2, all raised to the exponent y (or the y th power) There is one final term that you should describe to your
students in this lesson. To
Evaluate 4
4
Evaluate the expression ( x + 3)
Substitute 3 for x in the expression. ( x + 3) The processes of assigning variables to quantities and of translating between verbal and algebraic expressions are fundamental in algebra. |