Reflection of the line x+y+1=0 in the line lx+my+n=0 is
(x+y+1)(l+m)−2l2+m2(lx+my+n)=0
(x+y+1)l2+m2−2(l+m)(lx+my+n)=0
(l+m+1)(x+y)−2(lx+my)l2+m2=0
none of these
Required line is
(x+y+1)+λ(lx+my+n)=0 such that lx+my+n=0
is equally inclined to x+y+1=0 and this line.