Let f(x) = 4 sin² 3x.
- (a)Find the value of f' (π/4).[3]
- (b)Find ∫ f(x)dx.[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2024). The mark or mark type is shown in brackets.
- [M1] (a) Differentiate to obtain form ksin 3x cos3x or ksin 6x
- [A1] (a) Obtain correct 24sin3xcos 3x or 12 sin 6x
- [A1] (a) Substitute x = π/4 to obtain –12
- [M1] (b) Express integrand in form k₁ + k₂ cos 6x
- [A1] (b) Obtain 2 – 2 cos 6x
- [A1] (b) Integrate to obtain 2x – (1/3)sin6x
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