# Math Help - Solving Simultaneous Equations Using Matrices

1. ## Solving Simultaneous Equations Using Matrices

I've tried a problem for a very long time but I can't seem to get it right (my answer is different from the one in my textbook).

Could you please tell me where I went wrong?

Thank you!

2. Your inverse matrix is incorrect. You have correctly calculated the determinant but you also need to swap two entries and negate the other two.

$
\frac{-1}{106}\left[\begin{array} {cc} -10&-8 \\ -7&5 \end{array}\right]
\left[\begin{array} {cc} 5&8 \\ 7&-10 \end{array}\right]=
\left[\begin{array} {cc} 1&0 \\ 0&1 \end{array}\right]
$

3. Oh wait I'm sorry I did do the swapping and negating, I just forgot to include it in the image.

Could you show me how to solve it? Cause I still keep getting a wrong answer.