Answer:
2
Step-by-step explanation:
what you do is -4(2)^-2 which is -1
then you do 3(5)^0 which is 3
then you add it together and it is 2
-4x + y = 6
-5x - y = 21
add both of them
-9x = 27
x = -3
(-4*-3) + y = 6
-12 + y = 6
y = 18
Sector area = (central angle / 360) * PI * radius^2
sector area = (72 / 360) * PI * radius^2
radius^2 = sector area / [(72 / 360) * PI]
radius^2 = 16.2 * PI / [(1 / 5) * PI]
radius^2 = 16.2 / .2
radius^2 = 81
radius = 9
Source:
http://www.1728.org/radians.htm