Question

Solve e^(-0.2x)=4

Answer 1

Solve from x

Answer 2

*for

Answer 3

Use the natural log to get rid of the e, remember what you do to one side you must do to the other. Can you show me your work?

Answer 4

e^(-0.2x)=4
-0.2x=ln4
x=ln4/-0.2
x=-6.93
My math book is giving me a different answer

Answer 5

That is the answer that I get too

Answer 6

lot of that going around tonight

Answer 7

Oh well....I'll just hope for the best :)

Answer 8

I figured out why the book gave me a different number. Apparently, fractions with something like 0.2 in the denominator are a "no no" in math problems like these.
When I had x=ln4/.2 I should have realized the problem was saying....
\[\frac{ \ln 4 }{ 1} \div \frac{-1}{5}\] because .2=1/5.
If you solve this, you get -5 ln4