Question

Need help! :(

Answer 1

with?

Answer 2

\[T = 40e ^{-t/1500}\] find the value of T when t=240 and find t when T = 26.8

Answer 3

substitute t=240 in the first equation and calculate.

\[T= 40e^{-240/1500}\]

Answer 4

wow was i ever wrong!!

Answer 5

uh-oh @satellite73 i think, that was 't=240'.

Answer 6

Satellite, that's actually backwards. Not your fault, but they are using t and T as separate variables, which is dumb.

Answer 7

@satellite73 and wrong - HUNTO! - UNBELIEVABLE!!

Answer 8

yeah i was way way off

Answer 9

hey i am wrong fairly often

Answer 10

what's with all the bikes today?

Answer 11

\[\large T = 40e^{\frac{-t}{1500}} = 40e^{\frac{-240}{1500}}\]

Answer 12

I don't know, Satellite. I just don't like swimming upstream.

Answer 13

Where do you go from there SMoothmath?

Sorry :)

Answer 14

calculator

Answer 15

And to simplify that further, just use your calculator. Do e^(-240/1500), then multiply by 40. That will tell you T.

And for the other one, subsititute in for T instead of t, then use some algebra to solve for t. You'll need to take the natural log of both sides to get rid of the e.
\[\large 26.8 = 40e^{\frac{-t}{1500}}\]

Answer 16

You guys rock!

Answer 17

I know.

Answer 18

:P Enjoy your bikes! :D

Answer 19

http://www.wolframalpha.com/input/?i=40e^%28-240%2F1500%29

Answer 20

Thanks man.

Answer 21

Do you understand how to solve for t in the second case?

Answer 22

Yes, thank you :)

Answer 23

My pleasure =)

Answer 24

\[26.8 = 40e^{\frac{-t}{1500}}\]now the method is as i wrote in the first problem
divide by 40 get
\[.67=e^{-\frac{t}{1500}}\] write in logarithmic form as
\[\ln(.67)=-\frac{t}{1500}\] solve for \(t\) get
\[t=-1500\ln(.67)\] and then a calculator again

Answer 25

You guys are too cool,thanks again :)