/ 2 2\ 2 a*\b - a / - a *(a + b) ------------------------ / 2 2\ (a + b)*\b - a /
(a*(b^2 - a^2) - a^2*(a + b))/((a + b)*(b^2 - a^2))
/ 2 2 \ a*\b - a - a*(a + b)/ ----------------------- / 2 2\ (a + b)*\b - a /
a*(b^2 - a^2 - a*(a + b))/((a + b)*(b^2 - a^2))