x-3y=14 -(1)

4x+2y=0 -(2)

What is x & y?

thanks.

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- Dec 1st 2009, 01:25 AMs2951Simultaneous Equation
x-3y=14 -(1)

4x+2y=0 -(2)

What is x & y?

thanks. - Dec 1st 2009, 01:36 AMStroodle
Which part are you having trouble with?

From the first equation you can see that $\displaystyle x=14+3y$

So plug $\displaystyle 14+3y$ into the second equation in the place of $\displaystyle x$ then solve that for $\displaystyle y$. Once you have the value of $\displaystyle y$ plug that back into either equation to get the value of $\displaystyle x$.

Let us know if you have trouble with this. - Dec 1st 2009, 01:38 AMmrmohamed
- Dec 1st 2009, 01:46 AMs2951
- Dec 1st 2009, 01:54 AMBacterius
Wouldn't be useful here. Elimination method is only useful when the fact of adding or substracting together both equations gets rid of an unknown (like $\displaystyle -2x$ in the first one and $\displaystyle 2x$ in the second). Here you wouldn't get anything useful [I never ever use the elimination method, oddly enough I prefer using substitution in all problems ...] but if you are asked to do the Elimination method ...

- Dec 1st 2009, 02:53 AMRaoh
$\displaystyle \left\{\begin{matrix}

x-3y=14\\

4x+2y=0

\end{matrix}\right.$$\displaystyle \Leftrightarrow \left\{\begin{matrix}

x-3y=14\\

2x+y=0

\end{matrix}\right.$

Gauss Elimination,

$\displaystyle \Rightarrow \left\{\begin{matrix}

x-3y=14\\

14y=-56

\end{matrix}\right.$

Therefore,the solution is $\displaystyle [x=2,y=-4]$.