Evaluate Expressions Warm Up Lesson Presentation Lesson Quiz

Warm-Up Perform the indicated operation. 1. 12 1.5 ANSWER 8 2. 3.3 7 ANSWER 23.1

Perform the indicated operation. Warm-Up Perform the indicated operation. 3. 11.6 – 5.9 ANSWER 5.7 4. Julia ran 10 miles last week and 8 miles this week. How many more miles did she run last week? 2 3 5 6 ANSWER 1 mi 5 6

Evaluate the expression when n = 3. Example 1 Evaluate the expression when n = 3. a. 13 n = 13 3 Substitute 3 for n. = 39 Multiply. b. 9 n 9 3 = Substitute 3 for n. = 3 Divide. c. n – 1 = 3 – 1 Substitute 3 for n. = 2 Subtract. d. n + 8 = 3 + 8 Substitute 3 for n. = 11 Add.

Guided Practice Evaluate the expression when y = 2. ANSWERS 1. 6y 1. 12 2. 8 y 2. 4 3. y + 4 3. 6 4. 11 – y 4. 9

Example 2 Movies The total cost of seeing a movie at a theater can be represented by the expression a + r where a is the cost (in dollars) of admission and r is the cost (in dollars) of refreshments. Suppose you pay $7.50 for admission and $7.25 for refreshments. Find the total cost.

Example 2 SOLUTION Total cost = a + r = 7.50 + 7.25 = 14.75 ANSWER Write expression. = 7.50 + 7.25 Substitute 7.50 for a and 7.25 for r. = 14.75 Add. The total cost is $14.75 ANSWER

Guided Practice WHAT IF? In Example 2, suppose you go back to the theater with a friend to see an afternoon movie. You pay for both admissions.Your total cost (in dollars) can be represented by the expression 2a. If each admission costs $4.75, what is your total cost? The total cost is $9.50. ANSWER

Example 3 Write the power in words and as a product. Product Words Power a. 71 seven to the first power 7 b. 52 five to the second power, or five squared 5 5 c. 1 3 2 1 2 one half to the third power, or one half cubed d. z5 z to the fifth power z z z z z

Guided Practice Write the power in words and as a product. Product Words Power 6. 95 Nine to the fifth power 9 9 9 9 9 7. 28 Two to the eighth power 2 2 2 2 2 2 2 2 8. n4 n to the fourth power n n n n

Example 4 Evaluate the expression. a. x4 when x = 2 b. n3 when n = 1.5 SOLUTION a. x4 = 24 b. n3 = 1.53 = 2 2 2 2 = (1.5)(1.5)(1.5) = 16 = 3.375

Guided Practice Evaluate the expression. ANSWERS 9. x3 when x = 8 9. 512 10. k3 when k = 2.5 10. 6.25 11. d4 when d = 1 3 11. 1 81

The volume of the storage cube is 2744 cubic inches. Example 5 Storage cubes Each edge of the medium-sized pop-up storage cube shown is 14 inches long. The storage cube is made so that it can be folded flat when not in use. Find the volume of the storage cube. SOLUTION V = s3 Write formula for volume. = 143 Substitute 14 for s. = 2744 Evaluate power. The volume of the storage cube is 2744 cubic inches.

Guided Practice WHAT IF? In Example 5, suppose the storage cube is folded flat to form a square. Find the area of the square. The area of square is 196 in2. ANSWER

Lesson Quiz Evaluate the expression or power. 1. 13g when g = 7 ANSWER 91 2. 1.65 – a when a = 0.75 ANSWER 0.9 3. 54 ANSWER 625 1 3 4. ANSWER 1 27

Lesson Quiz Emily is saving for a $300 bicycle. She has saved $128.25. The amount she still needs to save is given by the expression c – s, where c is the cost of the bicycle and s is the amount she has saved. How much does she have left to save? 5. $171.75 ANSWER