Rearranging an equation using log functions

In summary, the conversation is about rearranging an equation using natural logarithms to the form y=a0 + a1*C. The attempt at a solution involved applying log laws, but there was confusion about whether multiple logs could be applied to each side. The goal was to use a program called polymath to determine the parameters X and K for a given set of data. The issue was resolved and the equation was successfully rearranged.
  • #1
Rosstickle
2
0

Homework Statement



Hi guys. I'm trying to rearrage an equation using the natural log and I thought I had it correct but am now struggling. I need to rearange it into the form: y=a0 + a1*C. Where a0 and a1 are some combination of the other variables and numbers below

Homework Equations



H = ((2^(X-1))-1)/(K*(X-1)*C^(X-1))

H,X,K and C are all variables

The Attempt at a Solution



I've tried rearanging using log laws but I now think it might be wrong.


ln(H) = ln(2^(X-1)-1) - ln(K*(X-1)) - (X-1)*ln(C)

But I'm not sure if this is legal considering the equation could be rearranged to:

H = (2^(X-1))/(K*(X-1)*C^(X-1)) - 1/(K*(X-1)*C^(X-1))

Can I then apply log as follows:

ln(H) = ln(2^(X-1))/(K*(X-1)*C^(X-1)) - ln(1/(K*(X-1)*C^(X-1)))

or can I only apply log once to each side, eg:

ln(H) = ln((2^(X-1))/(K*(X-1)*C^(X-1))- 1/(K*(X-1)*C^(X-1)))
 
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  • #2
ln(H) = ln(2^(X-1)-1) - ln(K*(X-1)) - (X-1)*ln(C)
H = (2^(X-1))/(K*(X-1)*C^(X-1)) - 1/(K*(X-1)*C^(X-1))
These two are fine. But
ln(H) = ln(2^(X-1))/(K*(X-1)*C^(X-1)) - ln(1/(K*(X-1)*C^(X-1)))
Is not right. You can only apply log once to each side (as you said), it would be:
ln(H) = ln((2^(X-1))/(K*(X-1)*C^(X-1))- 1/(K*(X-1)*C^(X-1)))

But What is it you are trying to do? Get C to be the subject of the equation?
 
  • #3
I was trying to rearrange it to the form:

y= a0 +a1*C

or

ln(y) = a0 + a1*ln(C)

I was trying to do this so a program called polymath could determine the a0 and a1 (using experimental date), so that I could find the parameters X and K for the given set of data.

I have since worked it out though. Thank you for your help anyway though.
 

1. How do you rearrange an equation using log functions?

To rearrange an equation using log functions, you can use the properties of logarithms such as the power rule, product rule, and quotient rule. These rules allow you to move terms containing logarithms to the other side of the equation and simplify the equation.

2. What is the purpose of rearranging an equation using log functions?

Rearranging an equation using log functions can help solve for a specific variable or simplify the equation. It can also make the equation more easily solvable by eliminating any exponential terms.

3. Can you provide an example of rearranging an equation using log functions?

Sure, let's say we have the equation y = log(x) + 2. To rearrange for x, we can use the power rule and subtract 2 from both sides, giving us y - 2 = log(x). Then, we can use the inverse of a logarithm, which is an exponent, to rewrite the equation as 10^(y-2) = x.

4. Are there any limitations to rearranging an equation using log functions?

Yes, there are a few limitations. First, the equation must contain logarithmic expressions. Second, you must be careful when taking the logarithm of both sides of an equation, as some solutions may not be valid for the original equation. Lastly, rearranging an equation using log functions may not always be the most efficient method for solving the equation.

5. How can I check if I have rearranged an equation using log functions correctly?

You can check your work by substituting the values you found for each variable back into the original equation and seeing if it satisfies the equation. You can also use a calculator to evaluate both sides of the equation and see if they are equal.

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