# Math Help - log and natural log

1. ## log and natural log

i have no idea if im doing this correct

400 = (1 - e^-.2t
ln400 = -.2tln(500(1- e)
.2t = ln(500(1 - e)
ln(400)

im stuck here, any help would be great

im trying to solve for T which indicates times in the problem

2. Originally Posted by jasimmons86
i have no idea if im doing this correct

400 = (1 - e^-.2t
ln400 = -.2tln(500(1- e)
.2t = ln(500(1 - e)
ln(400)

im stuck here, any help would be great

im trying to solve for T which indicates times in the problem

$400 = 1-e^{.2t}$

3. there shpould be a negative(-) before the .2

but otherwise yes

4. no, typed the equation wrong

here is the correct one

400 = 500(1-e^ -.2t)

solve for t

5. $1 - e^{-.2t} = \frac{400}{500}$

$1 = \frac{400}{500} + e^{-.2t}$

$1 = \frac{4}{5} + e^{-.2t}$

$1 - \frac{4}{5} = e^{-.2t}$

$\frac{1}{5} = e^{-.2t}$

$0.2 = e^{-.2t}$