For the equation: $-x^2 = -2x(3x+1)$ I can either multiply it out on the right side and get a $-6x^2-2x$ or just divide both sides by $-2x$. However, when divide out both sides, I just get one answer: $-2/5$. When I multiply it out, I get two answers: $-2/5$ and $0$.
What is wrong with dividing both sides by $-2x$??