Answer
$R=0$
$x-\dfrac {1}{2}$ is a factor.
Work Step by Step
$f\left( x\right) =2x^{4}-x^{3}+2x-1=\left( x-\dfrac {1}{2}\right) q\left( x\right) +R$
$\Rightarrow f\left( \dfrac {1}{2}\right) =0=R$
Since $R=0$, $x-\dfrac {1}{2}$ is a factor.