Problem 6.229

A radionuclide $A_{1}$ with decay constant $\lambda_{1}$ transforms into a radionuclide $A_{2}$ with decay constant $\lambda_{2}$. Assuming that at the initial moment the preparation contained only the radionuclide $A_{1}$, find: (a) the equation describing accumulation of the radionuclide $A_{2}$ with time; (b) the time interval after which the activity of radionuclide $A_{2}$ reaches the maximum value.