Algebra I Recipe: Variables in Algebra
A. Definitions
1. variable – any letter representing a number.
2. algebraic expression – an expression having numbers and variables with operations,
such as 2x - y.
B. How to Evaluate an Algebraic Expression
1. Substitute the given value in for each variable.
2. Perform the operations the same as evaluating numerical expressions in Sec. 1.1.
Examples:
 Evaluate 2g + 5 when g = 4.
 Evaluate 14(n + 1) when n = 2.
 Evaluate (x/7) + 16 when x = 14.

C. Formulas
1. 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
2. Temperature ºF = (9/5)ºC + 32
• ºF is degrees Fahrenheit
• ºC is degrees Celsius
3. 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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