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प्रश्न
Solve the pair of linear (simultaneous) equation by the method of elimination by substitution:
2x + 7y = 39
3x + 5y = 31
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उत्तर
2x + 7y = 39 ...(1)
3x + 5y = 31 ...(2)
2x + 7y = 39
∴ x = `[39 - 7y]/2`
Putting this value of x in (2)
`3([ 39 - 7y]/2) + 5y = 31`
`117 - 21y + 10y = 62`
`- 11y = - 55`
`y = 5`
From (1) x = `[39 - 7(5)]/2`
x = `4/2`
x = 2
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