Applications Of Derivatives Question 44
Question: The function $ f(x)=\cos x-2px $ is monotonically decreasing for
[RPET 1987; MP PET 2002]
Options:
A) $ p<\frac{1}{2} $
B) $ p>\frac{1}{2} $
C) $ p<2 $
D) $ p>2 $
Show Answer
Answer:
Correct Answer: B
Solution:
$ f(x) $ will be monotonically decreasing, if $ f’(x)<0 $ .
therefore $ f’(x)=-\sin x-2p<0 $
therefore $ \frac{1}{2}\sin x+p>0 $
therefore $ p>\frac{1}{2},,[\because -1\le \sin x\le 1] $ .
BETA
