| Chapter 8 Expressions and Equations 8-2 Evaluating Algebraic Expressions An algebraic expression can be evaluated by - Step 1: Assigning specific numerical values to all of the variables.
- Step 2: Completing all the operations
Example 1 Problem Evaluate the expression x + 4
when x = 2 | | | Procedure | | - Replace the given value of x in the expression.
| x + 4 = 2 + 4 | - Complete the operation.
| 2 + 4 = 6 | Solution x + 4 = 6
when x = 2. | | Example 2 Problem Evaluate the expression 6 – y
when y = 5 | | | Procedure | | - Replace the given value of y in the expression.
| 6 – y = 6 – 5 | - Complete the operation.
| 6 – 5 = 1 | Solution 6 – y = 1
when y = 5 | | Example 1 | 1. | - Step 1: Substitute 2 for the x in the expression: x + 4 becomes 2 + 6
- Step 2: Completing the addition operation: 2 + 4 = 6
| | 2. | Evaluate the expression: x – 5 when x = 8 - Step 1: Substitute 8 for the x in the expression: x – 5 becomes 8 – 5
- Step 2: Completing the operation: 8 – 5 = 3
| | 3. | Evaluate the expression: 2w + 11 when w = 3 - Step 1: Substitute 3 for the w in the expression: w – 5 becomes 2(3) + 11
- Step 2: Completing the operations: 2(3) + 11 = 6 + 11 = 17
- (Note: According to the rules of order of operations, you should do the muliplication first)
| | 4. | Evaluate the expression x/10 + 6 when x = 20 - Step 1: Substitute 20 for the x in the expression: x/10 + 6 becomes 20/10 + 6
- Step 2: Completing the operations: 20/10 + 6 = 2 + 6 = 8
- (Note: According to the rules of order of operations, you should do the division first)
| Exercises Click the ? symbol to see the correct answer. | 1. Evaluate x + 4 when x = 1. x + 4 = ? | 2. Evaluate x – 4 when x = 12. x – 4 = ? | | 3. Evaluate 12 – y when y = 5. 12 – y = ? | 4. Evaluate 3x + 1 when x = 3. 3x + 1 = ? | | 5. Evaluate k/4 – 1 when k = 12. k/4 – 1 = ? | Evaluating Expressions with More Than One Variable
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