I have no problems solving a determinant problem and getting to the principle diagonal but the case is different in a prove that question where it asks me to give a specific result, I have no idea how to start solving, I've tried searching for tips but with no luck so I found this website and I'm hoping I get help :)
for example, this problem:
Without expanding, prove that:
\begin{vmatrix} 1+a & 1 & 1 \\ 1 & 1+b & 1 \\ 1 & 1 & 1+c \\ \end{vmatrix} = abc ( $\frac 1a$ + $\frac 1b$ + $\frac 1c$ + 1 )
I don't need a solution, I need tips on how to deal with these kinds of questions, any help would be appreciated :)