| Exam Board | AQA |
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| Module | AS Paper 1 (AS Paper 1) |
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| Year | 2021 |
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| Session | June |
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| Topic | Chain Rule |
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9 A curve has equation
$$y = \frac { a } { \sqrt { x } } + b x ^ { 2 } + \frac { c } { x ^ { 3 } } \quad \text { for } x > 0$$
where \(a\), \(b\) and \(c\) are positive constants.
The curve has a single turning point.
Use the second derivative of \(y\) to determine the nature of this turning point.
You do not need to find the coordinates of the turning point.
Fully justify your answer.