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Mathematics

Solve :

32x+23y=13\dfrac{3}{2x} + \dfrac{2}{3y} = -\dfrac{1}{3}

34x+12y=18\dfrac{3}{4x} + \dfrac{1}{2y} = -\dfrac{1}{8}

Linear Equations

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Answer

Given, equations :

32x+23y=13\dfrac{3}{2x} + \dfrac{2}{3y} = -\dfrac{1}{3} …….(1)

34x+12y=18\dfrac{3}{4x} + \dfrac{1}{2y} = -\dfrac{1}{8} …….(2)

Multiplying equation (1) by 12\dfrac{1}{2}, we get :

12×(32x+23y)=12×1312×32x+12×23y=1634x+13y=16 ……..(3)\Rightarrow \dfrac{1}{2} \times \Big(\dfrac{3}{2x} + \dfrac{2}{3y}\Big) = \dfrac{1}{2} \times -\dfrac{1}{3} \\[1em] \Rightarrow \dfrac{1}{2} \times \dfrac{3}{2x} + \dfrac{1}{2} \times \dfrac{2}{3y} = -\dfrac{1}{6} \\[1em] \Rightarrow \dfrac{3}{4x} + \dfrac{1}{3y} = -\dfrac{1}{6} \text{ ……..(3)}

Subtracting equation (3) from (2), we get :

(34x+12y)(34x+13y)=18(16)34x34x+12y13y=18+16326y=3+42416y=124y=246=4.\Rightarrow \Big(\dfrac{3}{4x} + \dfrac{1}{2y}\Big) - \Big(\dfrac{3}{4x} + \dfrac{1}{3y}\Big) = -\dfrac{1}{8} - \Big(-\dfrac{1}{6}\Big) \\[1em] \Rightarrow \dfrac{3}{4x} - \dfrac{3}{4x} + \dfrac{1}{2y} - \dfrac{1}{3y} = -\dfrac{1}{8} + \dfrac{1}{6} \\[1em] \Rightarrow \dfrac{3 - 2}{6y} = \dfrac{-3 + 4}{24} \\[1em] \Rightarrow \dfrac{1}{6y} = \dfrac{1}{24} \\[1em] \Rightarrow y = \dfrac{24}{6} = 4.

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

32x+23×4=1332x+16=1332x=131632x=21632x=36x=3×62×3x=186=3.\Rightarrow \dfrac{3}{2x} + \dfrac{2}{3 \times 4} = -\dfrac{1}{3} \\[1em] \Rightarrow \dfrac{3}{2x} + \dfrac{1}{6} = -\dfrac{1}{3} \\[1em] \Rightarrow \dfrac{3}{2x} = -\dfrac{1}{3} - \dfrac{1}{6} \\[1em] \Rightarrow \dfrac{3}{2x} = \dfrac{-2 - 1}{6} \\[1em] \Rightarrow \dfrac{3}{2x} = \dfrac{-3}{6} \\[1em] \Rightarrow x = \dfrac{3 \times 6}{2 \times -3}\\[1em] \Rightarrow x = \dfrac{18}{-6} = -3.

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

32×3+23y=1312+23y=1323y=13+1223y=2+3623y=16y=2×63y=123=4.\Rightarrow \dfrac{3}{2 \times -3} + \dfrac{2}{3y} = -\dfrac{1}{3} \\[1em] \Rightarrow -\dfrac{1}{2} + \dfrac{2}{3y} = -\dfrac{1}{3} \\[1em] \Rightarrow \dfrac{2}{3y} = -\dfrac{1}{3} + \dfrac{1}{2} \\[1em] \Rightarrow \dfrac{2}{3y} = \dfrac{-2 + 3}{6} \\[1em] \Rightarrow \dfrac{2}{3y} = \dfrac{1}{6} \\[1em] \Rightarrow y = \dfrac{2 \times 6}{3} \\[1em] \Rightarrow y = \dfrac{12}{3} = 4.

Hence, x = -3 and y = 4.

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