how do you use the half life equation while trying to find the begining ammount?

Question

anonymous · Answer

u may have to use the natural logarithm / ln

anonymous · Answer

ok but u need to supply with info though

anonymous · Answer

sorry heading to bed now so won't be able to help u :( sorry abt that

anonymous · Answer

Let's say the half life equation is
    $$N(t) = N_0 (\frac{1}{2}) ^\frac{t}{Th}.$$
Then the inital amount N_0 is solved for, this way
    $$N_0 = N(t) \frac{1}{2}^{-\frac{t}{Th}}.$$
If you have time:t, current amount:N(t), and half life Th, N_0 can be calculated.

dumbcow · Answer

Sometimes the equation may also be represented as

P(t) = P_0*e^-kt

P_0 = P(t)*e^kt,  where k can be found if given the half life