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Mathematics

If x6+6=y,3x4=1+y\dfrac{x}{6} + 6 = y, \dfrac{3x}{4} = 1 + y, then :

  1. x = 12, y = 8

  2. x = 10, y = 8

  3. x = 8, y = 12

  4. x = 12, y = 6

Linear Equations

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Answer

Given,

Equations: x6+6=y,3x4=1+y\dfrac{x}{6} + 6 = y, \dfrac{3x}{4} = 1 + y

Solving first equation,

x6+6=y\dfrac{x}{6} + 6 = y

x+366=y\dfrac{x + 36}{6} = y

⇒ x + 36 = 6y

⇒ x = 6y - 36     …….(1)

Substituting value of x from equation (1) in 3x4=1+y\dfrac{3x}{4} = 1 + y, we get :

3(6y36)4=1+y18y108=4(1+y)18y108=4+4y18y4y=4+10814y=112y=11214=8.\Rightarrow \dfrac{3(6y - 36)}{4} = 1 + y \\[1em] \Rightarrow 18y - 108 = 4(1 + y) \\[1em] \Rightarrow 18y - 108 = 4 + 4y \\[1em] \Rightarrow 18y - 4y = 4 + 108 \\[1em] \Rightarrow 14y = 112 \\[1em] \Rightarrow y = \dfrac{112}{14} = 8.

Substituting value of y in equation (1), we get :

⇒ x = 6y - 36

⇒ x = 6(8) - 36

⇒ x = 48 - 36 = 12.

Hence, option 1 is the correct option.

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