The concentration, CCC, of a reactant in a non-isothermal chemical process is modeled by the function C=ϕ(t)C = \phi(t)C=ϕ(t), where ttt is the time in seconds. It is known that the graph of CCC against ttt has a point of inflection at t=12t = 12t=12. Given that ϕ′(12)=a\phi'(12) = aϕ′(12)=a and ϕ′′(12)=b\phi''(12) = bϕ′′(12)=b, where aaa and bbb are constants,
identify which of the following statements must be true:
ϕ′(12)=0 \phi'(12) = 0 ϕ′(12)=0 ϕ′′(12)=0 \phi''(12) = 0 ϕ′′(12)=0 ϕ′(12)≠0 \phi'(12) \neq 0 ϕ′(12)=0 ϕ′′(12)>0 \phi''(12) > 0 ϕ′′(12)>0Practise Edexcel A Level Maths Differentiation with exam-style questions for A Level Maths. 327 questions covering 12.1 Gradients of Curves, 12.2 Differentiation from first principles, 12.3 Differentiating x^n, 12.4 Differentiating Quadratics, 12.5 Differentiating functions with two or more terms, 12.6 Gradients, Tangents and Normals, 12.7 Increasing and Decreasing Functions, 12.8 Second Order Derivatives, 12.9 Stationary Points, 12.10 Sketching Gradient Functions, and 12.11 Modelling with Differentiation, 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.
