For math, I was given a quartic function. I was asked to find the coordinates of the points of inflection Q and R. Then to determine the points P and S, where the line QR intersects the quartic function again, and calculate the ratio PQ:QR:RS.

So I found the points of inflection. Easy.

Then I found the equation of the line through these 2 points. Very easy.

Then I set the quartic and this line equation equal, rearanging to get another quartic. I knew that there would be 4 roots to this quartic, 2 of which I have found as the points of infleciton, and 2 of which are the intersecting points I am looking for.

So I found this website, and went through the work of finding the points Q and R. I finally did, and checked my work using a graphing program, as well as the calculator on the site, and I didn't make any mistakes.

The problem is, I don't know how to explain what I've done. Finding all those variables and those strange formula's....can somebody PLEASE help me? I can't just say I used an online calculator to find the points, I had to show my work. The problem is I don't really know what I did according to that site.

http://www.1728.com/quartic2.htm

Thank you.