Need find variable from formula

[ecka333]

Hello, I have formula: CO2=3*KH*10^(7-PH). I need formula to find PH value when CO2 and KH values are known. Someone can help? Lately I will need to convert this formula to C# but I hope I will do this myself.

 

[Denis]

Hello, I have formula: CO2=3*KH*10^(7-PH).
I need formula to find PH value when CO2 and KH values are known.

Are those 3 variables only?
Can a = CO2, b = KH and c = PH,
such that we have: a = 3*b*10^(7-c), then solve for c ?

 

[ecka333]

Are those 3 variables only?
Can a = CO2, b = KH and c = PH,
such that we have: a = 3*b*10^(7-c), then solve for c ?

Yes, you understood my question well.

 

[JeffM]

[MATH] a = 3*b*10^{(7-c)} \implies 10^{(7-c)} = \dfrac{a}{3b} \implies \dfrac{10^7}{10^c} = \dfrac{a}{3b} \implies 10^c = \dfrac{3b * 10^7}{a}.[/MATH]
Now apply logs (easiest if you use logs to base 10). Can you do that?

 

[ecka333]

I need complete formula. I have finished school 22 years ago i am afraid i forgot about logarithms...

 

[Harry_the_cat]

Jeff's correct but I'd do it a little differently (and I've finished it off for you):

\(\displaystyle a = 3*b*10^{(7-c)}\)

\(\displaystyle \frac{a}{3b} =10^{(7-c)}\)

\(\displaystyle \log(\frac{a}{3b}) = 7-c\)

\(\displaystyle c = 7 - \log(\frac{a}{3b})\)

 

[ecka333]

Thanks, i will try it in the evening

 

[Denis]

\(\displaystyle c = 7 - \log(\frac{a}{3b})\)

integer solutions:
a,b,c
3,1,7
6,2,7
9,3,7