# Rearrange the formula.

• Aug 31st 2010, 11:24 PM
kiwisa
Rearrange the formula.
The formula is F= 35e^-0.7p

make p the subject.

Thanks in advance I am not sure where to start.

• Aug 31st 2010, 11:54 PM
Prove It
$\displaystyle F = 35e^{-0.7p}$

$\displaystyle \frac{F}{35} = e^{-0.7p}$

$\displaystyle \ln{\left(\frac{F}{35}\right)} = -0.7p$

$\displaystyle -\frac{10\ln{\left(\frac{F}{35}\right)}}{7}$.
• Sep 1st 2010, 04:19 AM
HallsofIvy
You "undo" what has been done to p.

$\displaystyle 35e^{-0.7p}= F$
The last thing done on the left is "multiply by 35" so the first thing you do to solve for p is divide both sides by 35:
$\displaystyle 35e^{-0.7p}/35= e^{-0.7p}= \frac{F}{35}$

Now, we have an exponential function (e to a power). The reverse of that is the "natural logarithm". Take the logarithm of both sides:
$\displaystyle ln(e^{-0.7p})= -0.7p= ln(\frac{F}{35})$

Finally, p is multiplied by -0.7. Divide both sides by -0.7:
$\displaystyle -0.7p/(-0.7)= p= -\frac{ln(\frac{F}{35})}{0.7}$