Answer:
Step-by-step explanation:
1. -35, 2
2. -72, -6
3. -16, 0
4. 40, 13
5. -15, 2
6. -30, 7
7. 30, 11
8. 42, -13
9. -3, -24
10. -4, 20
11. 7, 1
12. 4, -24
13. -7, -70
14. 4, 9
15. 7, -3
16. 9, 3
17. -10, 11
18. 6, -5
19. 11, 6
20. 1, -9
21. -9, 4
22. -8, 7
23. 6, 4
24. -7, -5
25. 11, 4
26. 10, 3
27. -8, 5
28. -9, 0
We can let
a = 1/(x-1)
b = 1/(y+2)
and rewrite the equations as
2a - b = 10
a + 3b = -9
Using the first to write an expression for b, we get
b = 2a - 10
Substituting this into the second equation gives
a + 3(2a -10) = -9
7a -30 = -9 . . . . . . . . simplify
7a = 21 . . . . . . . . . . .add 30
a = 3
b = 2·3 - 10 = -4
Now, we can find x and y.
3 = 1/(x -1)
x - 1 = 1/3
x = 1 1/3 = 4/3
-4 = 1/(y +2)
y +2 = -1/4
y = -2 1/4 = -9/4
Then the desired sum is
x + y = 4/3 -9/4 = (16 -27)/12
x + y = -11/12
The appropriate choice is ..
c. -11/12
This formula only applies if the track is circular. If it is, then we write the equation:
2*r*pi=400
Dividing by 2pi, we see that:
r=200/pi
This is approximately 63.66.
