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Thus, when ,
we set

Hence the plane is approaching the man with a speed of 500 km/hour. |
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Practice Exercises: Successive differentiation
1. Let , where and is differentiable and .Show that .
2. Show that for every ,
(i) 
(ii) 
3. Use Leibnitz theorem to find the third derivative of the functions
(i) 
(ii)  |