to find values of k for which the system is stable. s^4+2ks^3+2s^2+(1+k)s+2=0 first (1+k)must be >0 and 2K must be >0 then i construct routh array to get 3k-1/2k as a coefficent of s^2 and (3k-1)/2k *(1+k) - 4k as a coefficent of s . then k must be>1/3 and K>2.15 and K>-0.154 then k must be >2.15 ???? is this right or there is something wrong??