The line y = x/k + k, where k is a constant, is a tangent to the curve 4y = x² at the point P.
- (i)find the value of k,[3]
- (ii)the coordinates of P.[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2012). The mark or mark type is shown in brackets.
- [M1] Eliminates x or y completely (e.g., substitute y from line into curve)
- [M1] Uses b² - 4ac = 0 for a quadratic
- [A1] → k = -1
- [M1] Elimination of x or y (substituting k=-1 into line and curve equations)
- [M1] Soln of eqn. co. (for the coordinates)
- [A1] → P(-2, 1)
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