Simple math im not understanding

[qwerty11]

Heres the solution I have:

220*10^-3=(6/4.9)(1-e^((-t*4.9)/(140*10^-3))
e^(-4.9t/(140*10^-3))=08203
t=5.658

Could somebody expand this more for me please so I can see the mathematical operations to get to this solution?

 

[rock.freak667]

Heres the solution I have:

220*10^-3=(6/4.9)(1-e^((-t*4.9)/(140*10^-3))

Divide both sides by 6/4.9

e^(-4.9t/(140*10^-3))=0.8203

take ln of both sides of the equation

 

[qwerty11]

Divide both sides by 6/4.9



take ln of both sides of the equation

When I divide 220*10^-3 I don't get the same answer.

 

[Borek]

I got t=0.00566

 

[qwerty11]

Shouldn't it be 220*10^-3/(6/4.9)=x
lnx=lne^...
lne^/lnx
=ans??

 

[Borek]

What is ln(e^y)?