 So in this video, we're going to look at how to find the equation of a straight line. You should already know how to find the gradient, but if you've forgotten, watch this video first. So let's have a look at these three lines and their equations. If I gave you the gradient of all three, what two things can you see that links the straight line with its equation? Pause the video, have a think, and click play when you're ready to check. So did you see that the number in front of the x is the gradient? So negative three-quarters, negative two, and three. And the number on its own is where the line crosses the y-axis. We call this the y-intercept. It's where the line intercepts the y-axis. So here, the y-intercept is two, and negative three, and negative five. This is no coincidence. Straight lines are written in the format y equals mx plus c, where m is the gradient and c is the y-intercept. Give this question a go yourself. Find the equation of this straight line. Pause the video, work out the answer, and click play when you're ready to check. Did you get y equals 5x minus 4? If you got it right and want to skip the explanation, click here. Otherwise, keep watching. To start by finding the gradient, take two points on the line and use gradient equals rise over run. So 10 divided by 2 means the gradient is 5. And then the line crosses the y-axis at negative 4. So our equation is y equals 5x minus 4. So all you need to remember is that straight lines follow the y equals mx plus c format, where m is the gradient and c is the y-intercept. Y-intercept just means where the line crosses the y-axis. In another video, we're going to look at rearranging equations to make them fit the y equals mx plus c format, because this makes it really easy to find the gradient and the y-intercept. See you next time.