$\Delta=\left|\begin{array}{ccc}(a+1)(a+2) & a+2 & 1 \\ (a+2)(a+3-a-1) & 1 & 0 \\ a^{2}+7 a+12-a^{2}-3 a-2 & 2 & 0\end{array}\right|$
$=\left|\begin{array}{ccc} a ^{2}+3 a +2 & a +2 & 1 \\ 2( a +2) & 1 & 0 \\ 4 a +10 & 2 & 0\end{array}\right|$
$=4(a+2)-4 a-10$
$=4 a+8-4 a-10=-2$
$ 11 x+y+\lambda z=-5 $
$ 2 x+3 y+5 z=3 $
$ 8 x-19 y-39 z=\mu$
ને અસંખ્ય ઉકેલો હોય, તો $\lambda^4-\mu=$.............