Modify the Routh criterion so that it applies to the case in which all the poles are to be the left $-$ when $>0.$ Apply the modified test to the polynomial

$s^3+(0\mathrm{.}5+K)s^2+(1+2K)s+3K=0$

finding those values of $K$ for which all poles have a real part less than $-0\mathrm{.}7$