the change in y over the change in x is defined in calculus as: [tex] \frac{dy}{dx} [/tex] or you'll have it in delta: [tex] \frac{delta(y)}{delta(x)} [/tex] or Δy/Δx or if you have two points: [tex] \frac{y_2 - y_1}{x_2 - x_1} [/tex] and it is in simple term known as the slope.
