\(a\ge0\Rightarrow P=\frac{a}{\left(a-\frac{1}{2}\right)^2+\frac{3}{4}}\ge0\)
\(P=\frac{a^2-a+1-\left(a^2-2a+1\right)}{a^2-a+1}=1-\frac{\left(a-1\right)^2}{\left(a-\frac{1}{2}\right)^2+\frac{3}{4}}\le1\)
\(\Rightarrow0\le P\le1\)
Mà P nguyên \(\Rightarrow\left[{}\begin{matrix}P=0\left(a=0\right)\\P=1\left(a=1\right)\end{matrix}\right.\)