218 Answer Key

of a circle and can be any real nonzero number, so r is a variable. The numbers 2

and π have fi xed, defi nite values, so they are constants.

2. −12 is the numerical coeffi cient


3. 1 is the numerical coeffi cient
   4.^2
   3 is the numerical coeffi cient


4. −5x= −5 ⋅ 9 = − 45


5. 2xyz= 2(9)(−2)(−3) = 108
   7.^6
   510

6

5910

() 1 () 9 1

x

=

−

=

−

61 ⋅ 0

53 ⋅ 10

=

−

60

15 10

=

60

5

= 12

− ()−

−+

=

− + ()⋅ ()

− ()+()−

25 +

6

22 − (^5) ( −(−
(^3366) (()(− ()
y+ (^5) (
zy+

− + ()
− ()−
22 ⋅ (^5) ( +
(^6) (− 8

− +
− −
22 ⋅ 52 ⋅ 0
6 ()− 3 8
=−+
−
4 100
18 8

96
10
= 9.6

9. x^2 − 8x − 9 = 92 − 8 ⋅ 9 − 9
   = 81 − 72 − 9
   = 0


10. 2y + x(y − z) = 2(−2) + 9((−2) − (−3))
    = 2(−2) + 9 (−2 + 3)
    = 2(−2) + 9(1)
    =− 4 + 9
    = 5