# Homework Help: Solving for Im

1. Aug 22, 2010

### Matt007

1. The problem statement, all variables and given/known data

Hi,
I am trying to solve the equation for Im and am having trouble

$$Im=(Im+Ie+Ia)e^{-t/T} +Ia)$$

$$Im-Ia = (Im+Ie+Ia)e^{-t/T})$$

$$ln^{Im-Ia}= Im+Ie+Ia$$

this is were I get to but cant get the equation to work. Have I don't something incorrect in the second line when moving e^-t/T across to the other side?

Thanks

2. Aug 22, 2010

### Zryn

Going from the second to the third line, there's something wrong.

Keep in mind $$\frac{1}{e^{-x}}$$ = $$e^{x}$$. But expanding line 1 and rearranging the terms to make Im the focus may be the better alternative.

3. Aug 23, 2010

### HallsofIvy

Since you are not solving for t or T there is no reason to take a logarithm. Just treat $e^{-t/T}$ as a single number and divide both sides by it:
$$Ime^{t/T}- Iae^{t/T}= Im+ Ie+ Ia$$

Can you solve from there?

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