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# finding t watch

1. How do I find t from this
0.746=1-e^(-0.183t)
2. (Original post by dont)
How do I find t from this
0.746=1-e^(-0.183t)
It's best to isolate e^(-0.183t) first, do you have any ideas what you could do next?
3. (Original post by KaylaB)
It's best to isolate e^(-0.183t) first, do you have any ideas what you could do next?
Take 1 away to get -0.254 on the left?
4. (Original post by dont)
Take 1 away to get -0.254 on the left?
That is correct. Now you're going to want to get rid of the minus and apply a special function to both sides to get rid of the e. And then it becomes easy to deduce what t is
5. What subject is this for?
6. (Original post by Ano9901whichone)
What subject is this for?
Maths
7. How do you know it's not for physics?

(Original post by KaylaB)
Maths
8. (Original post by Sinfire)
That is correct. Now you're going to want to get rid of the minus and apply a special function to both sides to get rid of the e. And then it becomes easy to deduce what t is
so times both sides by -1. Im not sure what to do then. Do I take ln of both sides as I think that's the inverse to e.
9. Yes because ln(e) will end up giving u 1

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10. (Original post by dont)
so times both sides by -1. Im not sure what to do then. Do I take ln of both sides as I think that's the inverse to e.
Yes, ln is the reverse of e.

Once you've done that it will be fairly straightforward to work out t.
11. Thanks everyone

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