The equation of a curve is y = x⁻² ln x for x > 0. The curve has one stationary point.
- (a)Find the exact coordinates of the stationary point.[5]
- (b)Show that ∫(from 1 to e²) y dx = 18 ln 2 – 9.[5]
Mark scheme
Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.
- [M1] Use correct product rule or correct quotient rule
- [A1] Obtain correct derivative in any form
- [M1] Equate 2 term derivative to zero and solve for x
- [A1] Obtain answer x = e^(1/2)
- [A1] Obtain answer y = 1 / (2e)
- [*M1] Commence integration and reach -x⁻¹ ln x + ∫x⁻² dx
- [A1] Obtain -x⁻¹ ln x + -x⁻¹
- [A1 OE] Complete the integration and obtain -x⁻¹ ln x - x⁻¹
- [DM1] Use limits correctly in an expression of the form p x⁻¹ ln x + q x⁻¹ (pq ≠ 0)
- [A1 AG] Obtain 18 ln 2 – 9 from full and correct working
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