# Help me with the derivate of this equation?

1. Jul 15, 2005

### roboredo

Can sameone help me with the derivate of this equation?

y=a log10 (x) + B

Thank you
Marta

2. Jul 15, 2005

### dextercioby

What do you mean by "derivate this equation" ?

Daniel.

3. Jul 15, 2005

### roboredo

I am supposed to fit some data into this model (y= a log10 (x) + B, where a and b are constants), then I should calculate the slope of the isotherm in order to obtain an index

4. Jul 15, 2005

### dextercioby

1.You posted this problem in the wrong forum. The homework one is just above.
2.The slope is given by the derivative

$$y(x)=a\lg x+b \Rightarrow \frac{dy(x)}{dx}=...?$$

Daniel.

5. Jul 15, 2005

### roboredo

I am sorry, I have just realized it...which forum should I go to...general maths or homework?
But.. do you actually know the derivate of this equation?...

6. Jul 15, 2005

### roboredo

derivate

I am supposed to fit some data into this model
y= a log10 (x) + B, where a and b are constants
then I should calculate the slope of the isotherm in order to obtain an index

can someone help me?

Thank you , marta

7. Jul 15, 2005

### dextercioby

What's the connection between the logarithm base 10 and the logarithm base "e" ?

Daniel.

8. Jul 15, 2005

### roboredo

I am no mathematician nor student, i just need help to solve this for work purposes and I have no maths books around..the only tool I have is internet.

9. Jul 15, 2005

### dextercioby

Well, this is all you need

$$\lg x= \frac{\ln x}{\ln 10}$$

and now use the derivative of the natural logarithm.

Daniel.

10. Jul 15, 2005

### roboredo

i am still struggling!

11. Jul 15, 2005

### dextercioby

Well

$$\frac{d}{dx}\left(a\frac{\ln x}{\ln 10}\right)=\frac{a}{\ln 10}\frac{d \ln x}{dx}$$

Daniel.

12. Jul 15, 2005

### roboredo

I still haven't figured it out...
but thank you any way!

13. Jul 15, 2005

### ZapperZ

Staff Emeritus
In case you haven't noticed, I've mearged both of your threads into this one. So at some point, the "flow" of the thread may not make any sense.

:)

Zz.

14. Jul 15, 2005

### da_willem

$$\frac{a}{ln10} \frac{1}{x}=(\frac{a}{2.302585...} ) \frac{1}{x}$$