The second part to find the f(x) is wrong because c is not 0. ( In solution we find that c must be 0 if d is not 0. But this is a contradiction.)
My solution is still right.
The second part to find the f(x) is wrong because c is not 0. ( In solution we find that c must be 0 if d is not 0. But this is a contradiction.)
My solution is still right.