A scientist models the activity, AAA MBq, of a radioactive isotope over time, ttt days, using the equation
A=(15t+2)e−0.4t,t≥0 A = (15t + 2)e^{-0.4t}, \quad t \ge 0 A=(15t+2)e−0.4t,t≥0Find, using calculus, the exact value of ttt for which the activity is stationary.
30 exam-style questions on OCR (MEI) A Level Maths 1.9.12 Product rule (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.