| Exam Board | Edexcel |
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| Module | PMT Mocks (PMT Mocks) |
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| Topic | Chain Rule |
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3. The curve \(C\) has equation
$$y = 8 \sqrt { x } + \frac { 18 } { \sqrt { x } } - 20 \quad x > 0$$
a. Find
i) \(\frac { d y } { d x }\)
ii) \(\frac { d ^ { 2 } y } { d x ^ { 2 } }\)
b. Use calculus to find the coordinates of the stationary point of \(C\).
c. Determine whether the stationary point is a maximum or minimum, giving a reason for your answer.