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≥0A = (15t + 2)e^{-0.4t}, \quad t \ge 0A=(15t+2)e−0.4t,t≥0
Find, using calculus, the exact value of ttt for which the activity is stationary.
Practise Edexcel A Level Maths 9.4 The Product Rule with exam-style questions for A Level Maths. 30 questions, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.