<Table> <Tr> <Td> <P> − d N N = λ d t (\ displaystyle - (\ frac (\ mathrm (d) N) (N)) = \ lambda \ mathrm (d) t) </P> </Td> </Tr> </Table> <Tr> <Td> <P> − d N N = λ d t (\ displaystyle - (\ frac (\ mathrm (d) N) (N)) = \ lambda \ mathrm (d) t) </P> </Td> </Tr> <P> − d N N = λ d t (\ displaystyle - (\ frac (\ mathrm (d) N) (N)) = \ lambda \ mathrm (d) t) </P> <P> The negative sign indicates that N decreases as time increases, as the decay events follow one after another . The solution to this first - order differential equation is the function: </P>

How long will a nucleus undergo radioactive decay