A radionuclide A1 with decay constant 1 transforms into a radionuclide A2 with decay constant 2. Assuming

Question:

A radionuclide A1 with decay constant λ1 transforms into a radionuclide A2 with decay constant λ2. Assuming that at the initial moment the preparation contained only the radionuclide A1, find:
(a) The equation describing accumulation of the radionuclide A2 with time;
(b) The time interval after which the activity of radionuclide A2 reaches the maximum value.