Algebra I Recipe: Variables in Algebra 

A. Definitions

variable – any letter representing a number.

algebraic expression – an expression having numbers and variables with operations,
such as 2x  y.
B. How to Evaluate an Algebraic Expression
 Substitute the given value in for each variable.
 Perform the operations the same as evaluating numerical expressions in Sec. 1.1.



C. Formulas
 Interest Earned I = Prt
 Interest = Principal · rate · time
 Rate – must be in decimal form
 Time – must be in years such as 6 months = 0.5 years
 Temperature ºF = (9/5)ºC + 32
 ºF is degrees Fahrenheit
 ºC is degrees Celsius
 Distance d = rt
 distance = rate · time
 time – must be in hours such as 15 minutes = 0.25 hours
Practice Problems

G Redden


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