This video shows how to find areas between curves. The basic idea is that we find the space trapped between two curves on a graph. The formula for finding this is top curve, subtract bottom curve and then integrate. The presenter shows a parabola that goes through the origin. Then he draws a line that runs through the origin. We try to find the area trapped between the two. You take your smallest x co-ordinate to the largest x co-ordinate, you take the curve on top (2x) and subtract the curve on the bottom (-4x) and that's the interval you have to calculate.