x cube plus kx plus 9=0

Question

I took it as: x^3+kx+9=0
I answered:
If so.........

x^3+kx+9=0

Subtract 9 from both sides (Somenoe correct me if I'm wrong, please) which looks like:

x^3+kx+9-9=0-9
Now the best part.... finding variables

x^3+kx=9

x^3+(k•x)=9
Hmmm...

x^3= (x•x•x)

x•x•x•x+k=9

I'm not sure how to proceed....
How would I do this? I want to learn while I'm answering questions...
Thank you!
- Anonymous