new way to make quadratic equations easy

08062021, 05:32 PM
(This post was last modified: 08072021 09:49 AM by C.Ret.)
Post: #12




RE: new way to make quadratic equations easy
(08042021 04:57 AM)Benjer Wrote: I was surprised to learn that roots for quadratic equations could be solved using a slide rule, described in the manual for the Post Versalog: I was also really surprise, so I grasp my father's Graphoplex REITZ n°620 and it's very short manual where no mention about how to solve a quadratic equation is present. So I reinserted this manual in the red cardboard box and try the two examples. Here is a capture for the resolution of the first example : \( x^2+10x+15=0 \) . The trick is to mentally add value form the CI and the D scale. I get a hard time to found at which position I have to start seeking. To help me, I move the hairline (the middle hairline in red) to look for a sum as close as 10 as possible. Finally, the position of the middle hairline indicate the two roots on the CI and D scale respectively. [attachment=9708] (Note: the HP15C armed with quadratic solving code is only showing one root at a time). For the second example of equation \( x^2–12.2x17.2=0 \), I check with an HP Prime to have the two roots on the display. I only realize after a few attempts, that since there is no CIF and DF scale on this slide rule I need to use the right index of CI set on 17.2 on the D scale. Then, the procedure is usingthe D and CI scales but the substraction have to match 12.2 as close as possible. [attachment=9709] P.S.: Please note that on this slide rule, scale CI and D have respectively black B and red a labels (original Graphoplex: French Règle à Calculs). EDIT: Is that a new way to make the quadratic equation solving esay ?  new ? With a slide rule from 1958 ?  easy ? scanning for adding or substrating values on D and CI scale ? 

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Messages In This Thread 
new way to make quadratic equations easy  Bill Duncan  07302021, 01:44 AM
RE: new way to make quadratic equations easy  Maximilian Hohmann  07302021, 11:42 AM
RE: new way to make quadratic equations easy  Ren  07302021, 01:46 PM
RE: new way to make quadratic equations easy  Namir  07312021, 04:22 AM
RE: new way to make quadratic equations easy  C.Ret  07312021, 10:19 AM
RE: new way to make quadratic equations easy  Albert Chan  08012021, 03:08 PM
RE: new way to make quadratic equations easy  Namir  07312021, 07:03 AM
RE: new way to make quadratic equations easy  Namir  08012021, 07:56 AM
RE: new way to make quadratic equations easy  Benjer  08042021, 04:57 AM
RE: new way to make quadratic equations easy  C.Ret  08062021 05:32 PM
RE: new way to make quadratic equations easy  Namir  08062021, 12:40 AM
RE: new way to make quadratic equations easy  Ren  08062021, 02:22 PM

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