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Mathematics

Solve the following pairs of linear (simultaneously) equations using method of elimination by substitution:

2x + 3y = 8
2x = 2 + 3y

Linear Equations

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Answer

Given,

Equations : 2x + 3y = 8 and 2x = 2 + 3y

⇒ 2x + 3y = 8

⇒ 2x = 8 - 3y

⇒ x = 83y2\dfrac{8 - 3y}{2} …………(1)

Substituting value of x from equation (1) in 2x = 2 + 3y, we get :

2×(83y2)=2+3y83y=2+3y3y+3y=826y=6y=66=1.\Rightarrow 2 \times \Big(\dfrac{8 - 3y}{2}\Big) = 2 + 3y \\[1em] \Rightarrow 8 - 3y = 2 + 3y \\[1em] \Rightarrow 3y + 3y = 8 - 2 \\[1em] \Rightarrow 6y = 6 \\[1em] \Rightarrow y = \dfrac{6}{6} = 1.

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

x=83×12=832=52=2.5\Rightarrow x = \dfrac{8 - 3 \times 1}{2} \\[1em] = \dfrac{8 - 3}{2} \\[1em] = \dfrac{5}{2} = 2.5

Hence, x = 2.5 and y = 1.

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