Question

A good question-I would like to present

Answer 1

define \[D _{f}=I\] where f(1)=2
and satisfied with \[f(x-y ^{2})=f(x)+(y ^{2}-2x)f(y)\] at every Integer x and y
find f(100)

a.100 b.10,000 c.200 d.20,000

P.S.I made choices up ;P