48. Physics The radius of a water molecule is about 1.4 angstroms. One angstrom is 0.00000001 cm. What is the diameter of a water molecule in centimeters? Use scientific notation.
49. Reasoning Explain how the exponent of 10 changes when you multiply a number written in scientific notation by 100. Show an example.

C Challenge

50. Economics Gross domestic product (GDP) is a measure of the economic output of a country. The GDP of the United States was about 1.2 × 10 13 1.2 times , 10 to the thirteenth  dollars in 2005. This is about 3 times the U.S. GDP in 1985. What was the U.S. GDP in 1985?
51. Write 1 300 1 300th  in scientific notation.

Standardized Test Prep

SAT/ACT

52. A lab sample has a mass of 0.000345 g. What is this amount written in scientific notation?

    1. 0.345 × 10 3 0.345 , times , 10 cubed
    2. 0.345 × 10 − 3 0.345 , times , 10 super negative 3 end super
    3. 3.45 × 10 − 4 3.45 , times , 10 super negative 4 end super
    4. 3.45 × 10 4 3.45 , times , 10 to the fourth

53. What is the union of {1, 3, 5, 7} and {3, 4, 5}?

    6. {}
    7. {1, 7}
    8. {3, 5}
    9. {1, 3, 4, 5, 7}

54. What is the equation of the graph below?

    1. y = 2 x − 1 2 y equals 2 x minus , 1 half
    2. y = − 2 x − 1 2 y equals negative 2 x minus , 1 half
    3. y = 1 2 x − 1 2 y equals , 1 half , x minus , 1 half
    4. y = − 1 2 x + 2 y equals negative , 1 half , x plus 2

    

Short Response

55. A student is collecting cans to raise money for a class trip. Each week the student collects 150 cans. Make a graph of the situation. How many weeks will it take the student to collect 1200 cans?

Mixed Review

See Lesson 7-1.

Simplify each expression.

56. c d − 6 c , d super negative 6 end super
57. a 0 b 3 eh to the , b cubed
58. 9 w − 3 9 w super negative 3 end super
59. 4 m n − 5 fraction 4 m , over n super negative 5 end super end fraction
60. 3 − 2 k − 5 fraction 3 super negative 2 end super , over k super negative 5 end super end fraction

See Lesson 6-5.

Graph each linear inequality.

61. y < − 1 4 x + 2 y less than negative , 1 fourth , x plus 2
62. y ≥ 2 3 x y greater than or equal to , 2 thirds , x
63. y < 3 x − 4 y less than 3 x minus 4
64. y > − 3 x + 1 2 y greater than negative 3 x plus , 1 half

Get Ready! To prepare for Lesson 7-3, do Exercises 65-70.

See page 794.

Rewrite each expression using exponents.

65. t · t · t · t · t · t · t t middle dot t middle dot t middle dot t middle dot t middle dot t middle dot t
66. ( 6 − m ) ( 6 − m ) ( 6 − m ) open 6 minus m close open 6 minus m close open 6 minus m close
67. ( r + 2 ) ( r + 2 ) ( r + 2 ) ( r + 2 ) open r plus 2 close open r plus 2 close open r plus 2 close open r plus 2 close
68. 5 · 5 · 5 · s · s · s 5 middle dot 5 middle dot 5 middle dot s middle dot s middle dot s
69. 2 · 2 · 2 · 2 · 2 · x · x · x 2 middle dot 2 middle dot 2 middle dot 2 middle dot 2 middle dot x middle dot x middle dot x
70. 8 · 8 · ( x − 1 ) ( x − 1 ) ( x − 1 ) 8 middle dot 8 middle dot open x minus 1 close open x minus 1 close open x minus 1 close

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