I was using WolframAlpha to find a polynomial of degree up to $2$ that best fits the points $(-1,2),(0,0),(1,-2),(2,-4)$. The answer I was expecting is $$0x^2-2x+0.$$ However, here is what WoldframAlpha shows me:
I do not understand the term $3.70074\times 10^{-17}x^2$ is this problem. May I know by what algorithm does WolframAlpha get this term?