How do you find the solution of the system of equations $y = 3 x + 7$ $y=3x+7$ and $y = x - 9$ $y=x-9$ ?

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Answer 1 · 2015-05-02T04:52:58

We can substitute $y = x - 9$ $y = x-9$ in the first equation to get the value of $x$ $x$

We get $x - 9 = 3 x + 7$ $x - 9 = 3x +7$

Transposing $3 x$ $3x$ to the left hand side and $- 9$ $-9$ to the right hand side, we get

$x - 3 x = 7 + 9$ $x - 3x = 7 + 9$

$- 2 x = 16$ $-2x = 16$

Dividing both sides by $- 2$ $-2$ , we get

$(cancel(-2)x)/cancel(-2) = 16/-2$

$color(green)( x = -8$

Substituting $x=-8$ in the second equation, we get

$y = -8 - 9$

$color(green)( y = -17$

How do you find the solution of the system of equations y=3x+7y=3x+7y=3x+7 and y=x-9y=x−9y=x-9?