Question 178117
4a + 9b + 0 =  8
8a + 0  + 6c= -1
0  + 6b + 6c= -1
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Subtract twice the 1st equation from the 2nd to get:

4a + 9b   +  0 =  8
0  - 18b  +  6c= -17
0  + 6b   +  6c= -1
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Subtract the 3rd equation from the 2nd to get:
4a + 9b   +  0 =  8
0  - 24b  +  0= -16
0  + 6b   +  6c= -1
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Solve for "b" in the 2nd equation:
b = 16/24 = 2/3
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Substitute into the 1st to solve for "a" and into the 3rd to solve for "x".
4a + 9(2/3) = 8
4a + 6 = 8
4a = 2
a = 1/2
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6b + 6c = -1
6(2/3) + 6c = -1
4 + 6c = -1
6c = -5
c = -5/6
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a = 1/2
b = 2/3
c = -5/6
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Cheers,
Stan H