The concentration of a specific catalyst in a bioreactor, C C\,C mg/L, is monitored over a 12-hour production cycle. The concentration at time t t\,t hours, for 0≤t≤120 \le t \le 120≤t≤12, is modeled by the function:
C=t20(24+10t−t2)+5C = \frac{\sqrt{t}}{20}(24 + 10t - t^2) + 5C=20t(24+10t−t2)+5
Given that C C\,C has a stationary value at t=αt = \alphat=α:
Use calculus to show that α \alpha\,α satisfies the equation
5α2−30α−24=05\alpha^2 - 30\alpha - 24 = 05α2−30α−24=0
Hence find the value of α\alphaα, giving your answer to 3 decimal places.
Use further calculus to prove that C C\,C is a maximum at this value of α\alphaα.
Practise Edexcel A Level Maths 9.9 Using Second Derivatives with exam-style questions for A Level Maths. 57 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.