- #1

- 38

- 0

## Homework Statement

Use the given matrices to find (AB)^-1

(These are 2 X 2 matrices, please ignore the fraction bar in between the top and bottom elements. I can't figure this stupid latex piece of crap out)

A[tex]^{-1}[/tex] = [tex]\left(\frac{\frac{1}{2}}{\frac{-1}{2}} \ldots \frac{\frac{-5}{2}}{\frac{3}{2}}\right)[/tex]

B[tex]^{-1}[/tex] = [tex]\left(\frac{\frac{2}{3}}{\frac{-1}{3}} \ldots \frac{\frac{4}{3}}{\frac{5}{2}}\right)[/tex]

## Homework Equations

Only the one for inverse matrices which states,

(AB)[tex]^{-1}[/tex] = B[tex]^{-1}[/tex]A[tex]^{-1}[/tex]

## The Attempt at a Solution

The answer I get in the end is:

(AB)[tex]^{-1}[/tex] = [tex]\left(\frac{\frac{-1}{3}}{\frac{-17}{12}} \ldots \frac{\frac{1}{3}}{\frac{55}{12}}\right)[/tex]

But the book gets,

(AB)[tex]^{-1}[/tex] = [tex]\left(\frac{\frac{-1}{3}}{-1} \ldots \frac{\frac{1}{3}}{\frac{10}{3}}\right)[/tex]

Am I the one doing something wrong, or is the book wrong?

Any help would be greatly appreciated.

Thanks!