 So, it's another video on graphs. Can you match these four graphs to their equations? Pause the video, have a think, and click play when you're ready to check. Did you get it right? You should already know that this is a straight line because the highest power of X is one. And this positive quadratic, X squared, is a U-shaped curve. And the X cubed is a cubic. And so it looks like this. So then, by default, this equation must go with this graph. These are known as reciprocal functions, a number divided by X. And these are the reciprocal graphs. You may be thinking, why do we care about reciprocal functions that actually they're really important? Starting with Isaac Newton, he deduced that the forces needed to hold planets in orbits is a reciprocal relationship with the squares of their distances. So, as the distance between two planets increases, the gravitational force decreases. Other examples are radioactive isotopes decay reciprocally and trees losing their leaves. So, going back to the graphs, why do they split into two separate parts? Let's have a look at Y equals one over X in more detail. So we have our table of values, and if we substitute in these X values into Y equals one over X, we get these values. See how as X gets smaller, so closer to zero, the Y values get bigger. This means that when X gets really close to zero, Y would be very large, impossible to write a number so large. So then for when X is actually zero, you can't divide by zero, there is no value. The graph gets closer and closer to the Y axis, but it never touches it. The graph also gets closer and closer to the X axis and also never touches it. This is the same reasoning. If we rearrange the equation, it would be X equals one divided by Y. And again, you cannot divide by zero. Just on a side note, notice how the graph has two lines of symmetry. So from this video, you should know that reciprocal graphs look like this. They bend towards a horizontal and vertical line, but they never quite touch it. So the shape always stays the same, but it could be shifted and a negative reciprocal looks like this. So you should now confidently be able to recognize a straight line, a quadratic, a cubic, and a reciprocal function. Bye.