3. Consider the vector space $P_2$, the set of all polynomial functions of degree less than or equal to 2. Note that for real numbers $a_2, a_1, a_0$, the function $f(x) = a_2x^2 + a_1x + a_0$ is an element of $P_2$. Determine if the set of vectors given by $W = \{x^2 - x, x - 1, x^2 + 1\}$ spans $P_2$.