Variable Expressions
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Key Questions

Variables are symbols representing some changing quantities.
I hope that this was helpful.

Variable expressions are expressions that involve variables, which are symbols that represent changing quantities. (See http://socratic.org/questions/whatarevariables for reference). The value of the expression will change as the value of the variable changes.
For example, let's say with have the equation
#x + 5# When
#x = 1 # , then#x + 5 = 6# When
#x = 2 # then#x+5 = 7# Hope that was helpful.

To write variable expressions on Socratic, simply place hash tags around the expression when typing it:
[hash tag] x + 1 [hash tag] =
#x +1# [hash tag] (x1)/(x+1) [hash tag] =
#(x1)/(x+1)# Hope that was helpful.

To evaluate a variable expression means to find the value of the expression when the variable is (or variables are) replaced by a number (or numbers).
Here is a variable expression:
#3x+7# .To evaluate this expression when
#x = 2# mean to substitute#2# in place of#x# , and find the number (the value). [see note below]#3(2)+7 = 6+7 = 13# .When
#x=2# , the expression has a value of `#13# .If we evaluate the same expression when
#x=10# , we get:#3(10)+7 = 30+7 =37# .Here's a variable expression with two variables :
#3x2y# In order to evaluate this expression, we'll need values (numbers) for both
#x# and#y# .Evaluate the expression
#3x2y# when#x=4# and#y=5# #3(4)2(5) = 12  10 = 2# If we change the values to
#x=5# and#y=4# , we get
#3(5)2(4) = 15  8 =7# .Note:
To avoid saying exactly the same thing over and over, we use the following to mean the same thing:
evaluate the expression when
#x = 2#
evaluate the expression for#x = 2#
evaluate the expression at#x = 2#
evaluate the expression assuming#x = 2#
evaluate the expression if#x = 2# Also
If there is only one variable in an expression, we don't always need to mention it:
evaluate the expression for#2#
evaluate the expression at#2#
Questions
Expressions, Equations, and Functions

1Variable Expressions

2Expressions with One or More Variables

3PEMDAS

4Algebra Expressions with Fraction Bars

5Patterns and Expressions

6Words that Describe Patterns

7Equations that Describe Patterns

8Inequalities that Describe Patterns

9Function Notation

10Domain and Range of a Function

11Functions that Describe Situations

12Functions on a Cartesian Plane

13Vertical Line Test

14ProblemSolving Models

15Trends in Data