# help with determinant problem....

• Jan 15th 2009, 11:04 AM
JoanneMac
help with determinant problem....
Ok, here it is. I know how to do every single problem dealing with determinants except THIS one. This problem you have to solve the equation for 'x'. (Worried)

|0 0 -1|
| 3 x 0 | = x^2
| 2 0 3 |

Any help is appreciated!

• Jan 15th 2009, 11:15 AM
earboth
Quote:

Originally Posted by JoanneMac
Ok, here it is. I know how to do every single problem dealing with determinants except THIS one. This problem you have to solve the equation for 'x'. (Worried)

|0 0 -1|
| 3 x 0 | = x^2
| 2 0 3 |

Any help is appreciated!

Calculate the determinant. You'll get

$\left|\begin{array}{ccc}0&0&-1\\3&x&0\\2&0&3\end{array}\right| = 2x$

That means you have to solve for x:

$2x = x^2~\implies~x^2-2x=0~\implies~x(x-2)=0~\implies~x=0~\vee~x=2$