Routh-Array (Control Engineering)
I think in your question there are two special cases that you need to take care while you are approaching to solve this problem.

First thing is that in case if your entire row is zero than you need to take the coefficient of previous row and differentiate it in order to obtain the coefficients of the new row.

Second thing is that if you are geeting a zero in the first column of your routh array then you need to approximate it by a small no e (eplison) and then  after calculating all the limits you need to find its limit as epsilon tends to zero..

Using these two properties i hope it will be a lot easier to arrive at your answer .

Hope this helps!!