Matematika Jika a, b, c memenuhisistem persamaan a + 2b - c = 92a - b + 3c = -2-a + b + 2c = -1Nilai a, b, c berturut – turut adalah ... ​

loniemohrulv – March 08, 2023

Jika a, b, c memenuhisistem persamaan  
a + 2b - c = 9
2a - b + 3c = -2
-a + b + 2c = -1
Nilai a, b, c berturut – turut adalah ... 
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Jawaban:

a + 2b - c = 9 |x2| 2a + 4b - 2c = 18

2a - b + 3c = -2 |x1| 2a - b + 3c = -2

_____________-

5b - 5c = 20

a + 2b - c = 9

-a + b + 2c = -1

____________+

3b + c = 8

5b - 5c = 20 |x3| 15b - 15c = 60

3b + c = 8 |x5| 15b + 5c = 40

____________-

-20c = 20

c = -1

3b + c = 8

3b + (-1) = 8

3b = 9

b = 3

a + 2b - c = 9

a + 2(3) - (-1) = 9

a + 6 + 1 = 9

a + 7 = 9

a = 2

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