Question

Solve 3x – 7y = 25 using matrices.
5x – 8y = 27

(25, 27)

(27, 25)

(-1, -4)

(4, 1)

Answer 1

\[\left[\begin{matrix}3 & -7\\5&-8\end{matrix}\right] \left(\begin{matrix}x \\ y\end{matrix}\right) = \left(\begin{matrix}25 \\ 27\end{matrix}\right)\]
Now find the inverse of the first matrix and multiply.

Answer 2

11?

Answer 3

what 11?

Answer 4

that wat i got

Answer 5

Oh, it is the determinant(?)

Answer 6

yah

Answer 7

Okay, do you know how to find the inverse of a matrix?

Answer 8

i make b and c negative right?

Answer 9

Inverse of \[\left[\begin{matrix}a & b \\c & d\end{matrix}\right]\]
is
\[\frac{ 1 }{\left| A \right| } \left[\begin{matrix}d & -b \\ -c &a\end{matrix}\right]\]
where /A/ is the determinant.