# We have#f=X^3-5X^2+a,ainRR#.How to prove that #f# has at most a root in #ZZ#?

##### 1 Answer

Jul 13, 2018

See below

#### Explanation:

The Rational root theorem states the following: given a polynomial with integer coefficients

all the **rational** solutions of

Since, in your case,

So, you can't have more than