Can someone verify I've done party (d) correctly?

http://img267.imageshack.us/img267/1910/capturehaw.jpg

(a1+1)+(a2+2)t=0

This gives the system:

a1+1=0

a2+2=0

So,

a1=-1

a2=-2

So the set of all vectors for which L(a1,a2)=0 is:

N(L)={(a1,a2)|a1=-1 and a2=-2}

Thanks!