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प्रश्न
If 10y = 7x - 4 and 12x + 18y = 1; find the values of 4x + 6y and 8y - x.
उत्तर
10 y = 7x - 4
- 7x + 10y = - 4
- (7x - 10y) = 4
7x - 10y = 4 ...(1)
12x + 18y = 1 ...(2)
Multiplying equation no. (1) by 12 and (2) by 7.
84x - 120y = 48 ....(3)
84x + 126y = 7 ....(4)
Substract equation (3) and (4)
84x - 120y = 48
84x + 126y = 7
(-) (-) (-)
- 246 y = 41
y = `41/(- 246)`
y = - `1/6`
From (1)
7x - 10`(-1/6)` = 4
7x + `5/3` = 4
7x = `4 - 5/3`
7x = `7/3`
x = `7/3 xx 7`
x = `1/3`
∴ 4x + 6y = `4(1/3) + 6(-1/6) = 4/3 - 6/6 = 4/3 - 1 = 1/3`
∴ 8y - x = `8(-1/6) - 1/3 = -4/3 - 1/3 = -5/3`
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