(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

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

2. Relevant equations

3. 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.

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# Homework Help: Linear Algebra Homework Help

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