How do you use the rational root theorem to find the roots of #x^3+2x-9=0#?
1 Answer
Sep 22, 2015
The rational root theorem will only tell you what the possible rational roots are. This cubic has no rational roots.
Explanation:
By the rational root theorem, any rational root of
So the possible rational roots are:
#+-1# ,#+-3# ,#+-9#
None of these work.
Using Cardano's method, I found one Real root: