(i) 3x – y = 7; x + 4y = 11
Sol. 3x – y = 7;
x + 4y = 11
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D
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=
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3
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-1
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=
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(3 × 4) – (1 × - 1)
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=
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12 + 1
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=
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13
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1
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4
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DX
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=
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7
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-1
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=
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(7 × 4) – (11 × -1)
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=
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28 + 11
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=
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39
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11
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4
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DY
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=
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3
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7
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=
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(3 × 11) – (1 × 7)
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=
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33 - 7
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=
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26
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1
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11
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By Cramer's rule,
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x
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=
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Dx
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=
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39
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=
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3
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D
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13
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y
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=
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Dx
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=
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26
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=
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2
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D
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13
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x = 3 and y = 2 is the solution of given simultaneous
equations.
