Application of Derivatives 4 Question 23
24. The number of values of $x$, where the function $f(x)=\cos x+\cos (\sqrt{2} x)$ attains its maximum, is(1998, 2M)
(a) 0
(b) 1
(c) 2
(d) infinite
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Answer:
Correct Answer: 24. (a)
Solution:
- The maximum value of $f(x)=\cos x+\cos (\sqrt{2} x)$ is 2 which occurs at $x=0$. Also, there is no other value of $x$ for which this value will be attained again.
