A ) 5 x + y = 7 /*( -2 )
10 x + 2 y = 14
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- 10 x - 2 y = - 14
10 x + 2 y = 14
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0 x = 0 ( Dependent system )
B ) 5 x + y = 7 / * 3
- 15 x - 3 y = - 6
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15 x + 3 y = 21
- 15 x - 3 y = - 6
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0 x = 15 ( Inconsistent system )
C ) 5 x + y = 7
5 x + y = - 7 / * ( - 1 )
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5 x + y = 7
- 5 x - y = 7
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0 x = 14 ( Inconsistent system )
D ) 5 x + y = 7 / * ( - 2 )
6 x + 2 y = 7
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- 10 x - 2 y = - 14
6 x + 2 y = 7
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- 4 x = - 7; x = 7/4; y = - 7/4
Answer: the equation D ) would cause a consistent-independent system.
