Answer
$ x= \pm 1, \pm 5$ or $ x=-1,1,-5,5$
Work Step by Step
The Rational Root Test is defined as follows:
When a polynomial
$ f(x)=a_nx^n+a_{n-1} x^{n-1} +....+a_2 x^2+a_1x+a_0$ has integer coefficients, then every rational zero of $ f $ has the form $\dfrac{m}{n}$
where, $ m $ and $ n $ have no common factors other than $1$ and $ m $ is a factor of the constant term $ a_0$ and $ n $ is a factor of the leading co-efficient term $ a_n $.
So, $ f(x)=x^4-6x^3+14x^2-14x+5$ has possible rational roots:
$ x= \pm 1, \pm 5$ or $ x=-1,1,-5,5$
