The critical point is (-30,0) I think
No clue sorry i tried my best



Basically, you're looking for a matrix

such that

i.e. a matrix

whose nullspace with basis vector

.
By the rank-nullity theorem, the rank of

and the dimension of its nullspace must add up to the number of columns, so

One easy choice for a row would be

, since

Now you only need to find another combination such that the second row of

is independent of the first. An easy choice for this is to let the first element be 0, and the next be 1. Then the last element must be

, as

So,

is one possible solution.