⁸Recall from the previous section (“The Concept of Differentiation”) that velocity could be defined as the time-derivative of position: v = dx dt All we have done here is algebraically solved for changes in x by first multiplying both sides of the equation by dt to arrive at dx = v dt. Next, we integrate both sides of the equation in order to “un-do” the differential (d) applied to x: ∫ dx = ∫ v dt. Since accumulations (∫ ) of any differential (dx) yields a discrete change for that variable, we may substitute Δx for ∫ dx and get our final answer of Δx = ∫ v dt.