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September 20, 2025, 12:46:32 am
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Author Topic: Help on Exponential and Logarithmic modelling  (Read 760 times)  Share 

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tolga

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Help on Exponential and Logarithmic modelling
« on: February 09, 2010, 08:14:55 pm »
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Five grams of a radioactive substance is decaying so that the amount, A grams, that is left after t days, is given by the formula A=5e^-kt.

a) Find the value of A when the number of grams of the radioactive substance has been halved.
b) Rearrange the equation so that the t is the subject of the equation.

Note:Can you please show full working out
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the.watchman

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Re: Help on Exponential and Logarithmic modelling
« Reply #1 on: February 09, 2010, 08:18:55 pm »
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a)

b)





« Last Edit: February 09, 2010, 08:21:18 pm by the.watchman »
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tolga

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Re: Help on Exponential and Logarithmic modelling
« Reply #2 on: February 09, 2010, 08:29:50 pm »
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for part a what happened to e^-kt
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the.watchman

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Re: Help on Exponential and Logarithmic modelling
« Reply #3 on: February 09, 2010, 08:31:51 pm »
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Quote from: tolga on February 09, 2010, 08:29:50 pm
for part a what happened to e^-kt

It only asks for the value of A, which is the weight of what's left.
Therefore, A is half of the original amount (5 grams) and so is 5/2
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superflya

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Re: Help on Exponential and Logarithmic modelling
« Reply #4 on: February 09, 2010, 08:41:47 pm »
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lulz tolga dont make a question seem harder than it actually is :P some q's are very straightforward but are harder to pick up and people usually go wrong as they try and over-complicate things.
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the.watchman

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Re: Help on Exponential and Logarithmic modelling
« Reply #5 on: February 09, 2010, 08:42:44 pm »
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Quote from: superflya on February 09, 2010, 08:41:47 pm
lulz tolga dont make a question seem harder than it actually is :P some q's are very straightforward but are harder to pick up and people usually go wrong as they try and over-complicate things.

Lol, yeah superflya is right
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Remember, remember the 5th of November

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2011 - Eng - Phys - Chem - Spesh - Latin - UMAT
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