take the coefients and use gausian elimination
[tex] \left[\begin{array}{ccc}-1&4&|8\\-2&1&|9\end{array}\right] [/tex]
multiply top row by -2 and add to 2nd row
[tex] \left[\begin{array}{ccc}-1&4&|8\\0&-7&|-7\end{array}\right] [/tex]
divide bottom row by -7
[tex] \left[\begin{array}{ccc}-1&4&|8\\0&1&|1\end{array}\right] [/tex]
multiply bottom row by -4 and add to top row
[tex] \left[\begin{array}{ccc}-1&0&|4\\0&1&|1\end{array}\right] [/tex]
times top row by -1
[tex] \left[\begin{array}{ccc}1&0&|-4\\0&1&|1\end{array}\right] [/tex]
x=-4
y=1
dunno what the blanks are and the a0 and a1