Talk:Quadratic formula

message: The article could also mention somewhat simpler expressions for the y-coordinates of the vertex and the focus, and for the equation for the directrix, avoiding showing quantities in parentheses, and the negation thereof, based on the negation of the discriminant.
Vertex:
:\left ( \frac{-b}{2a},\frac{4ac-b^2}{4a} \right )
Focus:
:\left ( \frac{-b}{2a},\frac{4ac-b^2+1}{4a} \right )
Directrix:
:y=\frac{4ac-b^2-1}{4a}
...but I'm not insisting on it; just a suggestion. 2601:545:8201:6290:E445:9D52:D8D3:145F (talk) 23:29, 24 October 2020 (UTC)
thread_title:  Could mention simpler expressions for vertex, focus, and directrix 

message: In India, quadratic formula is popularly known as Shreedharacharya's formula (or Sridharacharya's formula) as it was first given by an ancient Indian mathematician Shreedharacharya (or Sridharacharya) or Sridhara around 1025 A.D. Huzaifa abedeen (talk) 14:23, 4 November 2020 (UTC)
thread_title:  Shreedharayacharya's formula 

message: Does there really need to be a citation at the end of the subsection "Method 3"?  AltoStev Talk 12:43, 27 October 2021 (UTC)
replies: text: Not really. But I did some cleaning up, removing reduncancies. There was nothing in the first part of subsection "Method 2" and in subsection "Method 3" that wasn't already there. - DVdm (talk) 13:33, 27 October 2021 (UTC)
thread_title:  Citation needed 

message: I noticed that, oddly, the article never seems to mention that the formula x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}  is only valid if the discriminant b^2 - 4ac is positive. Otherwise the right hand side of (2ax + b)^2 = b^2 - 4ac has no real root and the notation \sqrt{b^2 - 4ac} makes no sense (unless you explicitly define the notation \sqrt{x} as designating one of the two complex roots of x, but to my knowledge this notation is usually considered forbidden for numbers other than positive reals). Isn't this an important omission? So I tried to fix it --193.52.194.235 (talk) 11:10, 21 February 2022 (UTC)
replies: text: Complex numbers exist... Joao003 (talk) 12:33, 17 May 2023 (UTC)
replies: text: And if it's 0, you can just use one solution.......... Joao003 (talk) 12:36, 17 May 2023 (UTC)
replies: text: Yes, , doesn't have an obvious principle value when  is not a non-negative real number.  However , which is used in the quadratic formula, does meaningfully specify both square roots for all complex numbers.  (Well, it's a double root for , but you know what I mean.)  —Quantling (talk | contribs) 12:57, 17 May 2023 (UTC)
thread_title:  Sign of discriminant never mentioned ? 

message: There is a user named savage 1620 who had recently vandalised wikipedia page we request him to be blocked immediately David dclork li (talk) 13:38, 28 April 2023 (UTC)
thread_title:  Savage16 20 

message: I undid your edit because it left us with the same sentence twice in a row.  I suspect that your intent was otherwise; please make another edit accordingly.  —Quantling (talk | contribs) 12:54, 18 May 2023 (UTC)
replies: text: I think I figured out the intended edit, and have made it.  If I have failed, please accept my apologies.  —Quantling (talk | contribs) 13:42, 18 May 2023 (UTC)
replies: text: Nope, that's what I intended to do. Thanks! Graham87 14:27, 18 May 2023 (UTC)
thread_title: The Egyptian Berlin Papyrus

message: @Number 3434, I reverted your change to make the paragraph in the lead about the discriminant into a bullet list. I think this is too visually heavy and distracting at that spot, but it might be worth adding a separate section discussing it in greater detail (though I still would recommend against using a bullet list where paragraphs will do). There used to be a bullet list in the version of this article from a few months ago, special:permalink/1208763608, but I found the lead to be too long; remember, some readers just want a quick overview. You might also want to try expanding the part about quadratics at Discriminant or the part about disciminants at Quadratic equation. –jacobolus (t) 16:02, 30 April 2024 (UTC)
thread_title:  Discriminant with a bullet list