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14 votes
14 votes
−12x+y=−18−6x−3y=12 PLEASE HELp

User Haehn
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1 Answer

20 votes
20 votes

We want to find the solutions for the following system


\begin{cases}-12x+y=-18 \\ -6x-3y=12\end{cases}

We can start simplifying, by dividing all terms in the second equation by 3


\begin{cases}-12x+y=-18 \\ -2x-y=4\end{cases}

Now, we can add those equations together and get a new one only for x


\begin{gathered} -12x+y+(-2x-y)=-18+(4) \\ -14x=-14 \\ x=1 \end{gathered}

Now that we have the solution for x, we can substitute its value in any of the equations to get the value for y.


\begin{cases}x=1 \\ -2x-y=4\end{cases}\Rightarrow-2\cdot(1)-y=4\Rightarrow y=-6

And those are our solutions.


\begin{cases}x=1 \\ y=-6\end{cases}

User Daniel Kurka
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