The fuction D(t) is the determinant of a 4x4 matrix:

D(t) = |1 2 3 4|

|-1 0 -2 0|

|4 3 2 1|

|1 1 2 t|

Find the determinant D(t) and find the value t0 which gives D(t0) = 2/7

Thanks!

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- February 17th 2010, 04:32 PMgralla55Determinant problem
The fuction D(t) is the determinant of a 4x4 matrix:

D(t) = |1 2 3 4|

|-1 0 -2 0|

|4 3 2 1|

|1 1 2 t|

Find the determinant D(t) and find the value t0 which gives D(t0) = 2/7

Thanks! - February 17th 2010, 06:52 PMtonio
- February 17th 2010, 08:32 PMRoam
You could use the Laplace expansion, If you are confused about the method to be used for evaluating det of this 4x4 matix. Firstly, you choose any element or, if lacking, . Then you use as a pivot, apply elementary row [column] operations to put 0s in all other positions in column j [row i]. Then expand the determinant cofactors of column j [row i]. Let's see how you go.

- February 18th 2010, 06:51 AMgralla55
Ok thanks, I got the determinant to be 25. Still, how do I find the value t0 which gives D(t0) = 2/7 ?

- February 18th 2010, 12:38 PMgralla55
Isn't there any program which solves this type of problem? I just need the answer for a t0 which gives D(t0) = 2/7, no explanation needed :P

- February 18th 2010, 12:43 PMicemanfan
- February 18th 2010, 12:47 PMgralla55
"What you need is a way to write D(t) as a polynomial function of t."

Just realized that! But how? I have 1 hour to solve this, and I don't have my books here so I kinda need some help :P Would very much appreciate it! - February 18th 2010, 01:03 PMicemanfan
Just find the formula for calculating determinants of 4x4 matrices and apply it.

- February 18th 2010, 01:46 PMgralla55
Sure, but I don't have my books and that's why I'm asking :P Anyone? I have very little time left =( (10 hours)