This model can be used to predict the fuel consumption of a car, y y\,y miles per gallon, for a car travelling at x x\,x miles per hour.
y=k−0.015(x−50)2 y = k - 0.015(x - 50)^2 y=k−0.015(x−50)2where k>37.5k > 37.5k>37.5.
Calculate the fuel consumption, in miles per gallon, of a car travelling at 70 miles per hour. Give your answer in terms of kkk.
Deduce the speed at which the car has the greatest fuel efficiency.
State, giving reasons, the limitation on the values of x x\,x in terms of kkk.
211 exam-style questions on Edexcel A Level Maths Quadratics, covering 2.1 Solving Quadratics, 2.2 Completing the Square, 2.3 Sketching Quadratic Graphs, 2.4 The Discriminant, and 2.5 Modelling with Quadratics. Each one has a worked solution and a mark scheme showing where the marks go.