Expressions and Variables: Evaluating One Variable

-  To evaluate one variable expressions, find the variable and substitute a number for that variable.

-  Perform the arithmetic operations.

Examples:
Example 1.  Calculate this expression for . 
Solution: First, substitute for .
Then:
Now, use order of operation to find the answer:

Example 2.  Evaluate this expression for .  
Solution: First, substitute for .
Then:
Now, use order of operation to find the answer:

Example 3.  Find the value of this expression when . ()
Solution: First, substitute for ,
Then:

Example 4.  Solve this expression for .  
Solution: Substitute for .
Then: