I have the following matrix

$$\begin{pmatrix} 1 &-1 &α-1\\1 &1 &1\\ 2α & 2 & 4 \end{pmatrix}$$

I only have to set the determinant of this matrix to $0$. Then find values of $α$ when the determinant equals to $0$, and the values of $\alpha$ are correct?

  • 1
    The matrix is invertible when the determinant is not zero. So yes, find the values of $a$ for which the determinant is zero and that will give you the values for which it is not zero. – Mark Oct 11 at 12:14
  • There are several questions of this type already here on this site, e,g, here. Please look for duplicates before posting. – Dietrich Burde Oct 11 at 12:40

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