The diagram shows part of the graph of y = 16x + 27/x², which has a minimum at A. [Figure 11.1]
- (i)Find the coordinates of A.[4]
- (ii)The points P and Q lie on the curve y = 16x + 27/x² and have x-coordinates 1 and 3 respectively. Find the area enclosed by the curve and the line PQ. You must show all your working.[6]
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Mark scheme
Marking points from the official mark scheme (May/June 2018). The mark or mark type is shown in brackets.
- [M1] for dy/dx = 16 - P/x³
- [M1dep] Equating to zero and obtaining x³
- [A2] A1 for each
- [B1] B1 for both
- [B1] FT from their P and their Q
- [M1] for [px² + q/x]
- [A1] Integration correct
- [M1dep] for application of limits
- [A1] 12
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