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Question: Answered & Verified by Expert
The function $f(x)=\sin x-k x-c$, where $k$ and $c$ are constants, decreases always when
MathematicsApplication of DerivativesVITEEEVITEEE 2017
Options:
  • A $k>1$
  • B $k \geq 1$
  • C $k < 1$
  • D $k \leq 1$
Solution:
2442 Upvotes Verified Answer
The correct answer is: $k \geq 1$
Let $f(x)=\sin x-k x-c$ where $k$ and $c$ are constants
$f^{\prime}(x)=\cos x-k$ $\therefore f$ decreases if $\cos x \leq k$
Thus, $f(x)=\sin x-k x-c$ decrease always when $k \geq 1$

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