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How do you solve the simultaneous equations $x + 2 y = 5$ $x + 2y = 5$ and $3 x - 2 y + 7$ $3x - 2y + 7$ ?

1 Answer

Jul 24, 2015

$(x, y) = (3, 1)$ $(x,y) = (3,1)$

Explanation:

[1] $XXXX$ $color(white)("XXXX")$ $x + 2 y = 5$ $x+2y =5$
[2] $XXXX$ $color(white)("XXXX")$ $3 x - 2 y = 7$ $3x-2y = 7$

Adding [1] and [2]
[3] $XXXX$ $color(white)("XXXX")$ $4 x = 12$ $4x = 12$

Dividing by 4
[4] $XXXX$ $color(white)("XXXX")$ $x = 3$ $x = 3$

Substituting $3$ $3$ for $x$ $x$ in [1]
[5] $XXXX$ $color(white)("XXXX")$ $3 + 2 y = 5$ $3 + 2y = 5$

Simplifying
[6] $XXXX$ $color(white)("XXXX")$ $y = 1$ $y = 1$

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