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 one year ago
A certain radioactive element decays according to N=No e ^kt. If 50% of the original element sample remains after 9 days, what is the decay rate?
 one year ago
A certain radioactive element decays according to N=No e ^kt. If 50% of the original element sample remains after 9 days, what is the decay rate?

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satellite73
 one year ago
Best ResponseYou've already chosen the best response.2you know if \(t=9\) you have half of what you started with set \[e^{9k}=.5\] and solve for \(k\)

satellite73
 one year ago
Best ResponseYou've already chosen the best response.2you got this? solve in two steps only

openstudyhelpplease
 one year ago
Best ResponseYou've already chosen the best response.0how do you solve for k?

satellite73
 one year ago
Best ResponseYou've already chosen the best response.21) write in equivalent logarithmic form (take the log) 2) divide by 9

satellite73
 one year ago
Best ResponseYou've already chosen the best response.2\[e^{9k}=.5\iff 9k=\ln(.5)\iff k=\frac{\ln(.5)}{9}\]

satellite73
 one year ago
Best ResponseYou've already chosen the best response.2then if you want a decimal, use a calculator

openstudyhelpplease
 one year ago
Best ResponseYou've already chosen the best response.0i have no idea what that means haha. so is it: k= .1831?

openstudyhelpplease
 one year ago
Best ResponseYou've already chosen the best response.0wait is ln the button on the calculator for e?

satellite73
 one year ago
Best ResponseYou've already chosen the best response.2http://www.wolframalpha.com/input/?i=ln%28.5%29%2F9 usually \(ln\) is the button and \(e\) requires the shift key

openstudyhelpplease
 one year ago
Best ResponseYou've already chosen the best response.0ok, so i have to use the shift key right? i tried doing e ^.5 which was 1.64 and then divide that by 9 which was .1831

openstudyhelpplease
 one year ago
Best ResponseYou've already chosen the best response.0oh, the link helped. sorry we didn't learn this yet so I have no idea what im talking about

openstudyhelpplease
 one year ago
Best ResponseYou've already chosen the best response.0so the rate is k= 7.7 x 10 ^2
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