Question 29835
Hi,

There are two approaches to this. The obvious but quite long way is to let *[tex Y=\left(\begin{array}{cc}y_1&y_2\\y_3&y_4\end{array}\right)]. Then do the multiplication. You will get four equations and four unknowns, so with enough effort you can solve it. I'm not going to do this!

The more clever technique, and probably the way you are supposed to do it is to use a bit of matrix algebra. Because we know *[tex A] and *[tex B] we can work out *[tex A^{-1}] and *[tex B^{-1}]. Now let's take the equation and left multiply by *[tex A^{-1}] and right multiply by *[tex B^{-1}] we get.

*[tex A^{-1}AYBB^{-1}=A^{-1}CB^{-1}]

As you know *[tex XX^{-1}=I] for any invertable matrix *[tex X], so the equation simplifies to

*[tex Y=A^{-1}CB^{-1}]

Doing the multiplication you can work out *[tex Y]. If you have any trouble working out the inverses or doing the multiplication then please write back.

Hope that helps,
Kev