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Mathematics

Can x, y be found to satisfy the following equations simultaneously?

2y+5x=19,5y3x=1\dfrac{2}{y} + \dfrac{5}{x} = 19, \dfrac{5}{y} - \dfrac{3}{x} = 1, 3x + 8y = 5.

If so, find them.

Linear Equations

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Answer

Given,

2y+5x=19\dfrac{2}{y} + \dfrac{5}{x} = 19 ……(i)

5y3x=1\dfrac{5}{y} - \dfrac{3}{x} = 1 …….(ii)

3x + 8y = 5 …….(iii)

Multiplying eq. (i) by 5 and eq. (ii) by 2 we get,

10y+25x=95\dfrac{10}{y} + \dfrac{25}{x} = 95 ……(iii)

10y6x=2\dfrac{10}{y} - \dfrac{6}{x} = 2 …….(iv)

Subtracting (iv) from (iii) we get,

10y+25x(10y6x)=95225x+6x=9331x=93x=3193=13.\Rightarrow \dfrac{10}{y} + \dfrac{25}{x} - \Big(\dfrac{10}{y} - \dfrac{6}{x}\Big) = 95 - 2 \\[1em] \Rightarrow \dfrac{25}{x} + \dfrac{6}{x} = 93 \\[1em] \Rightarrow \dfrac{31}{x} = 93 \\[1em] \Rightarrow x = \dfrac{31}{93} = \dfrac{1}{3}.

Substituting value of x in (i) we get,

2y+513=192y+15=192y=4y=12.\Rightarrow \dfrac{2}{y} + \dfrac{5}{\dfrac{1}{3}} = 19 \\[1em] \Rightarrow \dfrac{2}{y} + 15 = 19 \\[1em] \Rightarrow \dfrac{2}{y} = 4 \\[1em] \Rightarrow y = \dfrac{1}{2}.

Substituting values of x and y in eq. (iii),

3×13+8×12=51+4=55=5.\Rightarrow 3 \times \dfrac{1}{3} + 8 \times \dfrac{1}{2} = 5 \\[1em] \Rightarrow 1 + 4 = 5 \\[1em] \Rightarrow 5 = 5.

Since, L.H.S. = R.H.S. hence, x=13 and y=12x = \dfrac{1}{3} \text{ and } y = \dfrac{1}{2} satisfies the equation.

Hence, equations can be satisfied simultaneously with x=13 and y=12x = \dfrac{1}{3} \text{ and } y = \dfrac{1}{2}.

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