Functions Question 638
Question: If $ f(x)=a\cos (bx+c)+d $ , then range of $ f(x) $ is
[UPSEAT 2001]
Options:
A) $ [d+a,\ d+2a] $
B) $ [a-d,\ a+d] $
C) $ [d+a,\ a-d] $
D) $ [d-a,\ d+a] $
Show Answer
Answer:
Correct Answer: D
Solution:
$ f(x)=a\cos (bx+c)+d $ ?..(i) For minimum $ \cos (bx+c)=-1 $ from (i), $ f(x)=-a+d=(d-a) $ For maximum $ \cos (bx+c)=1 $ from (i), $ f(x)=a+d=(d+a) $ \Range of $ f(x)=[d-a,d+a] $ .
BETA
