Consider the vector space $V=\{\begin{array}{c}{a}_0+a_{1}x+a_2{x}^2\text{:}{a}_i\text{i}\text{n}\text{R}\end{array}$ for $\{$:$i=0,1,2\}$ of polynomials of degree at most $2.$ Let $f$:$VR$ be a linear functional such that $f(1+x)=0,f(1-x^2)=0$ and $f(x^2-x)=2.$ Then $f(1+x+x^2)$ equals...