The equation of a curve is such that d²y/dx² = 2x – 1. Given that the curve has a minimum point at (3, –10), find the coordinates of the maximum point.
- The equation of a curve is such that d²y/dx² = 2x – 1. Given that the curve has a minimum point at (3, –10), find the coordinates of the maximum point.[8]
Mark scheme
Marking points from the official mark scheme (May/June 2014). The mark or mark type is shown in brackets.
- [B1] dy/dx = x² – x + c Correct integration (ignore +c)
- [M1 A1] = 0 when x = 3 → c = –6 Uses a constant of integration. co
- [A1] x² – x – 6 = 0 when x = –2 (or 3) Puts dy/dx to 0
- [B1/B1] y = ¹/₃x³ – ¹/₂x² – 6x (+k) √ first 2 terms, √ for cx.
- [M1] = –10 when x = 3 Correct method for k
- [A1] → k = 3.5 → y = 10.8 Co – r 10.8
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