3 ms·
The method is interesting, but what exactly is the intended use? I don't get what the OP is trying to do. - Normal people are going to forget any kind of proof
by qsort 5y ago
The method is interesting, but what exactly is the intended use? I don't get what the OP is trying to do.
- Normal people are going to forget any kind of proof you show them exactly eight seconds after you're done. The pedant in me wants to note that plugging the standard formula in and veryfing it works is also in fact a proof, but technically correct is, as always, the most useless kind of correct.
- Everyone solves quadratics by (a) eyeballing either zero, or (b) \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}. It just doesn't make any sense to use any other method when the standard formula is simple arithmetic you can do in your head.
- Students who are into kinky stuff like competitions already know several formulas for speed.
- If this is just pedagogical, it's basically a way to adamantly refuse to complete the square by using a slightly different way to complete the square
am I missing something? I'm open to change my mind.
- Tainnor 5y ago> Everyone solves quadratics by (a) eyeballing either zero, or (b) \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}. It just doesn't make any sense to use any other method when the standard formula is simple arithmetic you can do in your head. You have to remember the formula. I'm a maths student, but I can never remember it (and I also hate to memorize stuff). I remember the shape of it so that I could generally recognise it, but that's about it. I I need the general form, it's easy (for someone with practice) to rederive it from scratch. In practice, when given a quadratic equation, I can either guess its roots fairly quickly or I use completing the square. There are probably some other tricks, such as the one from the article, I could use and others undoubtedly use, but my method works for me, and it's not like I need to solve quadratic equations all the time.