Find all values of a that make det(A)=0.

Question

A={[a,a,4],[3,-2,-2],[5,1,a]}

Each set within the [ ] are the columns of matrix A.

Answer 1

Expand determinant of A using cofactors.

Set it equal to 0 and solve for the root(s) of your equation.

That will give you the a values where det(A)= 0