The diagram shows the graph of y = e^(sin 2x) cos 4x for 0 < x < 1/2π, and its maximum point M. [Figure 4.1]
- (a)Find the x-coordinate of M.[5]
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Mark scheme
Marking points from the official mark scheme (Oct/Nov 2025). The mark or mark type is shown in brackets.
- [M1] Use correct product rule: psin 4xesin2x + q cos2x cos4xesin2x
- [A1] Obtain derivative -4sin4xesin 2x +2cos2x cos4xesin2x
- [M1] Equate derivative to zero and obtain an equation in one trig function
- [A1] Obtain 2sin² 2x + 4sin2x -1=0
- [A1] Obtain x = 0.113 and no other root
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