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Mathematics

For solving each pair of equations, use the method of elimination by equating coefficients :

3 - (x - 5) = y + 2

2(x + y) = 4 - 3y

Linear Equations

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Answer

Simplifying first equation :

⇒ 3 - (x - 5) = y + 2

⇒ 3 - x + 5 = y + 2

⇒ 8 - x = y + 2

⇒ x + y + 2 - 8 = 0

⇒ x + y - 6 = 0 …….(1)

Simplifying second equation :

⇒ 2(x + y) = 4 - 3y

⇒ 2x + 2y = 4 - 3y

⇒ 2x + 2y + 3y = 4

⇒ 2x + 5y - 4 = 0 ……(2)

Multiplying equation (1) by 2, we get :

⇒ 2(x + y - 6) = 2 × 0

⇒ 2x + 2y - 12 = 0 …….(3)

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

⇒ 2x + 5y - 4 - (2x + 2y - 12) = 0

⇒ 2x - 2x + 5y - 2y - 4 + 12 = 0

⇒ 3y + 8 = 0

⇒ 3y = -8

⇒ y = 83-\dfrac{8}{3}.

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

x+y6=0x+(83)6=0x836=03x8183=03x26=03x=26x=263.\Rightarrow x + y - 6 = 0 \\[1em] \Rightarrow x + \Big(-\dfrac{8}{3}\Big) - 6 = 0 \\[1em] \Rightarrow x - \dfrac{8}{3} - 6 = 0 \\[1em] \Rightarrow \dfrac{3x - 8 - 18}{3} = 0 \\[1em] \Rightarrow 3x - 26 = 0 \\[1em] \Rightarrow 3x = 26 \\[1em] \Rightarrow x = \dfrac{26}{3}.

Hence, x = 263 and y=83\dfrac{26}{3} \text{ and } y = -\dfrac{8}{3}.

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