- #1
junsugal
- 6
- 0
Homework Statement
Consider the matrix A = 1 1 2 1
1 2 3 4
2 4 7 2t-6
2 2 6-t t
Find the values of t for which the matrix A is invertible
Homework Equations
The Attempt at a Solution
For A to be invertible, the determinant should not be 0.
So what I did is find the determinant of the 4x4 matrix.
Since this 4x4 matrix doesn't have any zero.
I find 4 3x3 determinants which leads to 3 2x2 determinants. And a total of 12 2x2 determinants.
After I sum all of them, my equation lead to 4t^2-7t+50 is not equals to zero.
And I can't solve for t.
This is weird because when I use online calculator for matrix, for t is 0,1,3, or any random number I put in, there is an inverse matrix.