How to factor the equation: $$x^2 + 2xy + y^2 - 2x - 2y - 15 = 0$$
I tried to solve this equation several times and looked for the reference about solving polynomial equations with two variables. I am confident to solve these type of equations without constant term at last. But with a constant term just like $(15)$ here, i couldn't solve it. Give it a try! and general approach to solve these type of equations.