7th Grade Math

R4 Selected Answers and Solutions

Selected Answers and Solutions

3333 ⎪^27 ⎥^ ÷^3 - ⎪-^4 ⎥^

= 27 ÷ 3 - 4 ⎪ 27 ⎥ = 27; ⎪- 4 ⎥ = 4

= 9 - 4 Divide.

= 5 Subtract.

37. Sometimes; it is always true if A and B are both
    positive or if A or B are negative, but not if both A
    and B are negative. 39. - ⎪ 7 + 3 ⎥ ; All others are
    positive. 41. C 43. C

Pages 83–85 Lesson 2-1C

1. (-2, -4); III
   33 From the origin, move no units horizontally,
   and up 3 units. (0, 3); the point lies on the y-axis.
   5–8. y

O x

6

8

5

7

9a. Sea Cliffs 9b. I 11. (5, 4); I 13. (4, -3); IV

1515 From the origin, more 3 units left, and up

5 units. (-3, 5); the point lies in Quadrant II

17. (0, -4); y-axis 19. (-4, -5); III 21. (1, 0); x-axis
    22–33. y

O x

(5, 6)

(8, 1)

(3, 0)

(7, - 8 )

(-5, - 7 )

(-1, - 7 )

(5, - 2 )

(-2, 10)

3

8

5 (-3, 7)

7 (0, 6)

.

4

9 (-4, 0)^2

6

1

/

:(0, - 5 )

35–37. y

123 x

:

;

9

4

2

3

4

1

O

3535 From the origin, move one and a half units to

the right. Then move up three and a half units.

39. Sample answer: Rene Descartes is often credited
    with inventing the coordinate plane and so the
    coordinate plane is sometimes called the Cartesian

plane, in his honor. 41. She switched the x- and

y-coordinates. She should have gone to the left

3 units and up 4 units. 43. Sample answer: Point A

is 1 unit to the right and 2 units down from the

origin, in Quadrant IV. Point B is 2 units to the left

and 1 unit up from the origin, in Quadrant II.

45. H 47. G

Pages 91–92 Lesson 2-2B

1. 
   
   
   
   • 14 3. 7 5. - 4
     77 -^17 +^20 + (-3)
     = (-17) + (-3) + 20 Commutative (+)
     = [(-17) + (-3)] + 20 Associative (+)
     = (-20) + 20 Add.
     = 0
   
   
   
   


2. 
   
   
   
   • 1 11. - 38 13. 16 15. 13 17. 5 19. - 4
   
   
   
   


3. 
   
   
   
   • 34 23. 3 25. - 14 + 3; -11; The shark is
     11 feet below sea level.
     2727 In a bank account, withdrawing $20 would be
   
   
   
   

• 20 and depositing $84 would be +84.
  152 + (-20) + 84 = (152 + 84) + (-20)
  = 236 + (-20)
  = 216
  The balance is $216.

29. green T-shirt: profi t of $1; white T-shirt: profi t of
    $3; black T-shirt: profi t of $3 31a. Additive Inverse
    Property 31b. Commutative Property (+)


30. x + (-4) 35. n + 6 37. - 8 + (-3) = - 11


31. G 41. (-2, 4); II 43. (-3, -1); III 45. +75 or
    75 47. - 13 49 - 12

Pages 97–98 Lesson 2-2D

1. 
   
   
   
   • 3
     33 -^4 -^8
     = - 4 + (-8) To subtract 8, add -8.
     = - 12 Simplify.
   
   
   
   


2. 24 7. - 2 9. - 21 11. 22 13. - 10 15. - 14


3. 
   
   
   
   • 14 19. - 30 21. 23 23. 31 25. 104 27. 6
   
   
   
   


4. 0 31. 0 33. 15 35. 11
   3737 a. 2,407 - (-8) = 2,407 + 8 or 2,415 ft
   b. 2,842 - (-282) = 2,842 + 282 or 3,124 ft
   c. 345 - (-282) = 345 + 282 or 627 ft
   d. 0 - (-8) = 0 + 8 or 8 ft


5. 16 41. Sample answer: - 5 - 11 = - 5 + (-11) =

• 16; Add 5 and 11 and keep the negative sign.

43. true 45. A 47. 7 49. - 13 51. Quadrant IV 53. 8

Pages 100–101 Lesson 2-3A

1. 24 free throws
   33 Each month, the amount of money Peter has
   increases by $35. Extend the pattern.
   Months 12345678
   Money
   Saved $50 $85 $120 $155 $190 $225 $260 $295
   So, it will take Peter 8 months to save $295.

R01_R42_EM_SelAns_895130.indd R4 1/18/10 9:50 AM