Hi

Can someone tell me where is my mistake, my solution doesn't agree with the book's answers.

1) Use Gaussian elimination, solve the equation for x and y:

$\displaystyle 2x+4y=-2$

$\displaystyle -x+3y=-7$

$\displaystyle \begin{bmatrix}

2 & 4 | & -2 \\

-1 & 3 | & 7

\end{bmatrix}$

2R2 - R1 -> R1

$\displaystyle \begin{bmatrix}

2 & 4 | & -2 \\

-1 & 3 | & 7

\end{bmatrix}$

R1 - R2 -> R2

$\displaystyle \begin{bmatrix}

2 & 4 | & -2 \\

-1 & 3 | & 7

\end{bmatrix}$

$\displaystyle -x+2y=16$

$\displaystyle x=2$

$\displaystyle y=-9$

correct answer is x=2.2 and y=-1.6

P.S