I am a math tutor looking for a better way to explain quadratics to my students.
I came across the so-called "Po-shen Loh" method on YouTube, and I tried to apply it to a quadratic equation that one of my students was having trouble with. (Here is the video that I learned it from, skipped to the example that is most similar to my problem: https://youtu.be/XKBX0r3J-9Y?t=1663)
The equation that I want to solve is $5x^2 - 4x - 6 = 0$
Here is the correct result, as confirmed by symbolab (https://www.symbolab.com/solver/quadratic-equation-calculator/solve%20for%20x%2C%205x%5E%7B2%20%7D-4x-6%3D0):
$$ x_{1,2} = \frac{2 \pm \sqrt{34}}{5} $$
However, when I try to work it out using the "Po-shen Loh" method, I keep getting this result:
$$ x_{1,2} = \frac{2 \pm \sqrt{40}}{5} $$