I need some help with this. There's no answer in the back of the book and I computed the inverse to check my answer and I keep getting it wrong.

http://img706.imageshack.us/img706/4346/desklu.jpg

Printable View

- Feb 13th 2010, 01:53 PMNoxide[SOLVED] Matrix Operations
I need some help with this. There's no answer in the back of the book and I computed the inverse to check my answer and I keep getting it wrong.

http://img706.imageshack.us/img706/4346/desklu.jpg - Feb 14th 2010, 03:19 AMHallsofIvy
"2 times row one of $\displaystyle A^{-1}$ minus row two of $\displaystyle A^{-1}$ plus 3 times row 3 of $\displaystyle A^{-1}$" is simply $\displaystyle \begin{bmatrix}2 & -1 & 3\end{bmatrix}A^{-1}$. But that is the second row of A. Multiplying the second row of A by $\displaystyle A^{-1}$ gives the second row of the identity matrix which is $\displaystyle \begin{bmatrix}0 & 1 & 0\end{bmatrix}$.

- Feb 14th 2010, 07:30 AMNoxide
ah ok got it