How to Find The Quadratic Equation From a Table/Points
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- Опубліковано 8 бер 2021
- So, those fun problems where you're given a table and asked, "Write the quadratic equation that represents the table/points shown?" That's what this video is all about.
Let me know if you have any questions or comments below. Thanks for watching!
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Very helpful as always! The video was a bit long but absolutely worth it. Great and detailed explanation, thank you very much
Yeah, it was a bit longer than I would have liked (working on that) but I'm glad it helped!
To find a, just divide the 2nd difference, which is 4, by 2. It always works! Less solving! Solve for b by substituting a, x, y, and c!
Absolutely! I teach the longer way initially because it also helps you practice solving systems of linear equations, which you’ll need in a typical Algebra 1 course and is taught before this topic. Once a student has that down, I’ll show them that trick as it’s definitely a time saver!
I like to jokingly tell students “Remember this technique when you get to calculus and you’ll see why it works!” 😄
@TopTierMath I get it. I had to learn algebra, geometry, and trigonometry because I wanted to be an engineer when I was in HS and college. Now, my daughter wants to be an artist and has zero interest in math. So, to get her through HS, I have "cheat sheets" and short cuts for her to memorize so she can pass it and get through it and graduate HS! Know what I mean?
@@paules0099 I initially majored in engineering, very cool! And yes, I definitely know what you mean. If you haven’t already, I would definitely recommend peppering in some SAT/ACT (whichever she will take) math questions so she gets the chance to think outside the standard “here’s your formula -> plug and chug” (more or less) and get exposed to the types of questions those exams ask.
Theres a lot of free/paid SAT/ACT prep questions with whatever difficulty you’d like to work on so I would always recommend my students to practice them.
@@justinm412 If you only knew my daughter, LoL. She is easily confused by numbers! Especially irrational numbers and radicals! Math was a serious issue since 1st grade! She passes math by short cuts. She has zero interest when it comes to numbers. And, quite frankly, when I worked in engineering, all that math I learned, went out the window went solving real world challenges I faced in the work force, know what I mean?
We can make it even simpler by finding 'a' which is just dividing second difference by 2......ie, here, 4/2=2...
Then use a point to get the value of 'c'
I love that method as well! My students generally aren't taught that way, but I show them that trick for future use ;)
Thank you! Ps: here’s another trick. The change of change in y (4 in your case) divided by 2 is always a.
Absolutely! My students generally don’t see that from their teachers, but as they get experience I like to show them that trick. Definitely a time saver!
what if the change of the change is not constant what do you do then?
Great question!
If you're asked to find a quadratic equation from a list/table of points, the change in the change will always be constant. Do you have a particular example that you'd like for me to do a video on?
@@TopTierMath Yes thank you so much! I have a table and the question is "Find the quadratic function that is the best fit for f(x) defined by the table" The X's are 0,2,4,6,8, &10 and the Y's are 0,397,1596,3601,6403, &9990. Thank you so much for responding I've been stuck on this.
@@chloesdeadinside8982 my apologies for the late response. Are you being asked to do this by hand or are you allowed to use a graphing calculator?
@@TopTierMath i think it might’ve been a too late response 😅😅
Thanks
You're very welcome!