Data Structures :: Hashing - Discussion

The hash function is
H1(k) = k % 50.
In the case of collision, the hash function used is
H(k) = (H1(k) + M x H2(k)) % 50
where H1(k) = k % 50 and H2(k) = k % 20.
M is initialized to 0 and is incremented by 1 each time a collision occurs.
This could be categorized under which of the following collision detection technic