>>11546852a tiny value would be added onto derivatives, for example, for the derivative of x^2 you would usually break it down into x * x, multiply the change in x by the other x and multiply the change in the other x by x, this change can be 1 because it gets amplified by the division anyway. so x * x, 1 * x, x * 1 = 2x, notice that we don't actually change any of the x values, this is because the change approaches 0. If it approaches the plank length then each x value gets changed by the plank length but the difference is that a change in one x affects the other. by this i mean, x*x, plank length * x, (x + plank length) * plank length which gives us 2planklengthx + planklength^2, which gets devided by plank length to give 2x + planklength