A) \[\left( 0,\frac{\pi }{2} \right)\]
B) \[\left( \frac{\pi }{2},\pi \right)\]
C) \[\left( \pi ,\frac{3\pi }{2} \right)\]
D) none of above
Correct Answer: A
Solution :
Consider \[f(x)=\frac{8}{\pi }x+\cos x+\cos 2x+\cos 3x\] \[f(0)=f\left( \frac{\pi }{2} \right)\,=3\]? \[\therefore \,\,f'(c)=0\] for some \[c\in \,(0,\,\,\pi /2)\]You need to login to perform this action.
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