JEE Advanced | 2013Application of DerivativeMedium
Question
Let f(x) = x sin π x, x > 0. Then for all natural numbers n, f′(x) vanishes at -
Options
A.a unique point in the interval 

B.a unique point in the interval 

C.a unique point in the interval (n, n + 1)
D.two points in the interval (n,n + 1)
Solution
Æ’′(x) = sinπx + π x cos π x = 0
tan π x = - p x
y = tanx π & y = - π x

intersection point lies in
..........
as well (n, (n + 1)) because root lies in

tan π x = - p x
y = tanx π & y = - π x

intersection point lies in
..........as well (n, (n + 1)) because root lies in

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