How can I explain to someone who is a beginner, the basic idea and intuition behind dy/dx? I'm introducing calculus to one of my friends and here are the questions I might encounter: Why dy/dx? What do I even need to find the slope? How does that relate to rate of change of y with respect to x? What could be some real life examples for a better understanding? What information does the slope at every point of a curve, which is just a line, give me?
I'd like to explain all of this giving an intuitive sense to the formal differential calculus. Thanks!