# Math Help - Radioactive Decay

A radioactive substance decays according to the law q(t)=q(sub0)e^(-ct), where q(sub0)=q(0). Find its half life if c=1000. Thanks for the help.

2. Originally Posted by nystudent2729
A radioactive substance decays according to the law q(t)=q(sub0)e^(-ct), where q(sub0)=q(0). Find its half life if c=1000. Thanks for the help.
there's a formula for this: $\text{half life } = \frac {\ln 2}c$

to see this, set $q(t) = \frac 12 q_0$ and solve for t