Variables x and y are related by the equation y = (5x-1) / (3-x).
- (i)Find dy/dx, simplifying your answer.[2]
- (ii)Hence find the approximate change in x when y increases from 9 by the small amount 0.07.[3]
Mark scheme
Marking points from the official mark scheme (May/June 2016). The mark or mark type is shown in brackets.
- [M1] Clear attempt at quotient rule or equivalent product rule
- [A1] dy/dx = 14/(3-x)² or dy/dx = 14/(x²-6x+9) cao or correct simplified equivalent
- [B1] [y = 9] x = 2
- [M1] condone 0.07 ≈ (dy/dx)[x=2] δx oe
- [A1] 0.005 oe
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