How do you solve $3 x + 6 y = - 6$ $3x+6y=-6$ and $- 7 x + y = 29$ $-7x+y=29$ using substitution?

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How do you solve $3 x + 6 y = - 6$ $3x+6y=-6$ and $- 7 x + y = 29$ $-7x+y=29$ using substitution?

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Answer 1 · 2018-04-01T18:57:24

$(x, y) = (- 4, 1)$ $(x,y)=(-4,1)$

Explanation:

Solve one of these equations for $y$ $y$ to make substitution possible. The second equation appears best suited for this:

$- 7 x + y = 29$ $-7x+y=29$

$y = 7 x + 29$ $y=7x+29$

We can now replace all instances of $y$ $y$ in the first equation with $7 x + 29 :$ $7x+29:$

$3 x + 6 (7 x + 29) = - 6$ $3x+6(7x+29)=-6$

$3 x + 42 x + 174 = - 6$ $3x+42x+174=-6$

$45 x = - 6 - 174$ $45x=-6-174$

$45 x = - 180$ $45x=-180$

$x = - \frac{180}{45}$ $x=-180/45$

$x = - 4$ $x=-4$

To find $y,$ $y,$ plug in the result above into either of the two equations. We solved the second one for $y,$ $y,$ so that will be the easiest one to use:

$y = 7 (- 4) + 29$ $y=7(-4)+29$

$y = 1$ $y=1$

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How do you solve $3 x + 6 y = - 6$ $3x+6y=-6$ and $- 7 x + y = 29$ $-7x+y=29$ using substitution?

1 Answer

Explanation:

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