Answer:a = - 2
b = - 3
c = 3
Step-by-step explanation:
a + 5b - c = - 20 - - - - - - - - - 1
4a - 5b + 4c = 19 - - - - - - - - - 2
-a - 5b - 5c = 2 - - - - - - - - - - - 3
Adding equation 1 and equation 2, it becomes
- 6c = - 18
c = - 18/ - 6 = 3
Multiplying equation 2 by 1 and equation 3 by 4, it becomes
4a - 5b + 4c = 19
-4a - 20b - 20c = 8
Adding both equations, it becomes
- 25b - 16c = 27
- 25b = 27 + 16c = 27 + 16 × 3
- 25b = 75
b = 75/- 25 = - 3
Substituting b = - 3 and c = 3 into equation 1, it becomes
a + 5 × - 3 - 3 = - 20
a - 15 - 3 = - 20
a - 18 = - 20
a = - 20 + 18 = - 2
