Applications Of Derivatives Question 421
Question: If x tends 0 to $ \pi $ , then the given function $ f(x)=x\sin x+\cos x+{{\cos }^{2}}x $ is
Options:
A) Increasing
B) Decreasing
C) Neither increasing nor decreasing
D) None of these
Show Answer
Answer:
Correct Answer: B
Solution:
$ f(x)=x\sin x+\cos x+{{\cos }^{2}}x $
$ \therefore f’(x)=\sin x+x\cos x-\sin x-2\cos x\sin x $
$ =\cos x(x-2\sin x) $
Hence $ x\to 0 $ to $ \pi $ , then $ f’(x)<0 $ i.e., $ f(x) $ is decreasing function.
BETA
