λ-3 & 12 & -1 \\
0 & λ+2 & λ \\
0 & 0 & 5
For what values of λ does matrix B have an inverse?
The Attempt at a Solution
I first tried to calculate det(B)=(λ-3)(5λ+10) +0 -0
to get x=-2 or 3.
I'm unsure if this calculation helps me, and what to do beyond this point.