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anonymous
 2 years 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?
anonymous
 2 years 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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anonymous
 2 years ago
Best ResponseYou've already chosen the best response.0you know if \(t=9\) you have half of what you started with set \[e^{9k}=.5\] and solve for \(k\)

anonymous
 2 years ago
Best ResponseYou've already chosen the best response.0you got this? solve in two steps only

anonymous
 2 years ago
Best ResponseYou've already chosen the best response.0how do you solve for k?

anonymous
 2 years ago
Best ResponseYou've already chosen the best response.01) write in equivalent logarithmic form (take the log) 2) divide by 9

anonymous
 2 years ago
Best ResponseYou've already chosen the best response.0\[e^{9k}=.5\iff 9k=\ln(.5)\iff k=\frac{\ln(.5)}{9}\]

anonymous
 2 years ago
Best ResponseYou've already chosen the best response.0then if you want a decimal, use a calculator

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

anonymous
 2 years ago
Best ResponseYou've already chosen the best response.0wait is ln the button on the calculator for e?

anonymous
 2 years ago
Best ResponseYou've already chosen the best response.0http://www.wolframalpha.com/input/?i=ln%28.5%29%2F9 usually \(ln\) is the button and \(e\) requires the shift key

anonymous
 2 years 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

anonymous
 2 years 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

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