Problem: Solving Vmax equation with HP Prime

07242018, 03:45 AM
Post: #1




Problem: Solving Vmax equation with HP Prime
Hi All
I recently got a HP Prime and am trying to solve a chemistry equation with little success. The formula appears below and calculating the result using traditional methods required two passes. V = (Vmax * S) / (Km +S) V and S are given and we need to calculate Vmax and Km Manually we solve first for Vmax and then substitute that answer into the equation again to resolve for Km I have tried countless ways of entering this in the Prime but I cannot get any valid results. Can someone provide guidance on how I would go about solving this in the HP Prime Thanks 

07242018, 04:57 PM
Post: #2




RE: Problem: Solving Vmax equation with HP Prime
At a glance, it appears that you are trying to solve for two unknowns (Vmax and Km) with a single equation. Is there a second equation that relates these two? Without a value for one of those, you (and your calculator) wouldn't be able to calculate the other unless there is another distinct equation to relate them.


07242018, 05:22 PM
Post: #3




RE: Problem: Solving Vmax equation with HP Prime
(07242018 03:45 AM)doun17 Wrote: Hi All You have two unknowns but only a single equation. You can't solve for two unknowns with only one equation (unless there are unusual side conditions). Being the equation linear, you can solve for Vmax in terms of Km or Km in terms of Vmax. Best, Aries 

07242018, 06:16 PM
(This post was last modified: 07252018 12:24 PM by roadrunner.)
Post: #4




RE: Problem: Solving Vmax equation with HP Prime
Is that the MichaelisMenten equation? If you have data for V and S plot 1/V vs 1/S in the statistic 2 variable app. If you use a linear fit the Y intercept is 1/Vmax, the slope is Km/Vmax and the x intercept is 1/Km.
edit: the x intercept is 1/Km road 

07252018, 02:14 PM
Post: #5




RE: Problem: Solving Vmax equation with HP Prime
Hi
Thanks to everyones contribution to my problem, I was able to find the solution to the MichaelisMenten equation. For those interested here is what I did. In CAS mode solve({48=v*0.2/k+0.2, 60=v*2/k+2},{v,k}) this gave the result of v=61.71 and k=5.71e2 The correct solution! 

07252018, 02:15 PM
Post: #6




RE: Problem: Solving Vmax equation with HP Prime
(07242018 06:16 PM)roadrunner Wrote: Is that the MichaelisMenten equation? If you have data for V and S plot 1/V vs 1/S in the statistic 2 variable app. If you use a linear fit the Y intercept is 1/Vmax, the slope is Km/Vmax and the x intercept is 1/Km. Yes this is the MichaelisMenten equation, see my next post for the solution. Thanks for your help 

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