A = a^2 + ab + b^2 + a - b + 1 = \dfrac{1}{2}(a^2 + 2ab + b^2) + \left (\dfrac{1}{2}a^2 + a + \dfrac{1}{2} \right) + \left (\dfrac{1}{2}b^2 - b + \dfrac{1}{2} \right) = \dfrac{1}{2}(a + b)^2 + \left(\dfrac{a}{\sqrt{2}} + \dfrac{1}{\sqrt{2}} \right)^2 + \left(\dfrac{b}{\sqrt{2}} -...