Let w be a k-form defined in an open set A of $\mathbb R^n$. We say that w vanishes on x if w(x) is the zero tensor.
Show that if w vanishes at each x in a neighborhood of $x_0$ then dw vanishes at $x_0$ I have no idea how to approach this question, please don't reveal the answer but provide intutive hints that will lead me to the solution. Thank you :)