Differential Equations

The differential equation $M(x, y) dx + N(x, y) dy = 0$ is exact if and only if:

Options:

• (A) $\frac{\partial M}{\partial y} = \frac{\partial N}{\partial x}$
• (B) $\frac{\partial M}{\partial x} = \frac{\partial N}{\partial y}$
• (C) $\frac{\partial M}{\partial y} = -\frac{\partial N}{\partial x}$
• (D) $M + N = 0$